Help me: Why won’t my newly assembled PC start or boot?

| January 10, 2010 | (71)

This is the last of three posts written specially for people who have built their computer but need help because it won’t power on or won’t boot.

  1. 10 tips for first time PC builders
  2. FAQ: How to Build Your own Computer
  3. Help me: Why won’t my newly assembled PC start?

Help me: Why won’t my newly assembled PC start?

There are plenty of reasons why a newly PC won’t start. Resolving an issue is usually fairly simple, the problem lies in finding it, which usually involves testing different possibilities.

Here’s what to look for to find the main problems:
(Note this is not an extensive list of all the problems/solutions, but rather a simple quick guide for the most common issues)

If the PC doesn’t power on at first:
This is most probably due to you forgetting to plug in a power cable/cord.

  • Is the power cord plugged into a wall outlet and into the power supply?
  • Is the power supply switched on?
  • Is the power lead cable (power SW) from the case plugged into the motherboard?
  • Make sure that all the power cables are plugged in. The video card may require one or two PCI-Express power connectors and the motherboard requires the 24-pin ATX connector along with the 4/8-pin ATX power.

If the PC still doesn’t power on after that:
This might be due to a broken power SW switch (Try using the reset one instead to see if that one does work.)
If the PC still doesn’t on even while trying the reset switch instead, the problem is most likely due to a defective power supply. Try an ATX Power Supply Tester ($10)

If the PC doesn’t boot (Power up, but nothing is displayed on the monitor):

  • Once again, make sure that all the power cables are plugged in. The video card may require one or two PCI-Express power connectors and the motherboard requires the 24-pin ATX connector along with the 4/8-pin ATX power. Other components such as hard drives and optical  drives also require dedicated power.
  • Make sure that memory modules are plugged where they should be, that is slot 1 and 3 (some motherboards work only with slot 2 and 4). Try one stick a time. Make sure that they are fully seated.
  • Double-check your video card to make sure that it is fully inserted.
  • Ensure that the motherboard stand-offs are installed correctly (including the insulation washers) and that the motherboard is not touching any part of the case.
  • Check your CPU for proper seating, and possibly a bent pin on the CPU or motherboard.
  • Think through everything you have done in the setup, even the heat sink and thermal paste.
  • If you have a speaker for the mother/case, listen to the beep code and find out the problem with your manual. You didn’t get a speaker with your case? Use this kit from FrozenCPU ($10)

If the PC still won’t boot:
1- Clear the CMOS: This can be done either with the jumper (located close to the battery on the motherboard) or by removing the battery.

2-Remove one component at a time, until the PC boot. The last component that was removed before it booted is most likely the problem. Try using an alternative part if possible, otherwise consider a return (RMA).

3- I recommend that you do your build outside of the case at first, so if you have a problem, it’s easier to troubleshoot. I would take the motherboard out of the case and just set it on the foam pad that came with the box that the motherboard came in. You can also set the pad on the actual box. You should not have to take the PSU out of the case, just set the case near the board.

Hook up the following:

  1. 24-pin main ATX power
  2. 8-pin 12v CPU power
  3. CPU cooler fan
  4. 1 stick of RAM in the first slot
  5. video card
  6. 6-pin/8-pin PCIe video card power connector(s)
  7. monitor
  8. mouse
  9. keyboard
  10. 2-pin f_panel POWER SW connector

The power sw comes from the case power switch and the proper connector should be labeled. The motherboard manual will say where it goes, and there should be something like “PSW” or “Power SW” printed on the board with a color code for the proper header.

Plug in the PSU, turn on the power switch, and push the power button. You may have to hold the power button down for a few seconds.

If that works, add one part back in at the time, while booting the PC every time. If it stops booting, it is most likely due to the last part that you inserted.

Additional Guides:

Here are three other guides to help you out if you need them:

  1. Computer Won’t Turn On from About.com
  2. How to Figure out Why a Computer Won’t Boot: 12 Steps from Wikihow
  3. Problem: Your Computer Won’t boot from PC World

Conclusion

If you still have problems with your PC not powering or not booting after using this guide, leave a post describing your problem and everything that you’ve tried on the forums and we’ll do my best to help you out.

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Category: How to, Questions & Answers

About Mathieu Bourgie: HR Founder - Computer expert with 13 years of experience in building, fixing and modifying PCs. Over the years, I’ve developed a passion for PC hardware and now I enjoy helping others build their own PCs! In April 2008, I launched Hardware Revolution and ... Read more at my about page .

  • http://www.gamersworldbd.com/ Mushfiqur Rahman@Gamersworldbd

    I had this funny problem. After assembling this new PC, it wouldn't boot. When I pressed the power switch nothing happened. But the motherboard light was on (the little green light). It was confusing, every cable and jumper were in place. I checked the power button and reset switch connection.

    The problem was with the power supply. Even though the PSU would turn on (fans spinnin) but it gave no power. Hope this tip helps. If your PC doesn't boot the main culprit is the PSU and unseated RAM (push it firmly in).

  • http://www.gamersworldbd.com/ Mushfiqur Rahman@Gamersworldbd

    I had this funny problem. After assembling this new PC, it wouldn't boot. When I pressed the power switch nothing happened. But the motherboard light was on (the little green light). It was confusing, every cable and jumper were in place. I checked the power button and reset switch connection.

    The problem was with the power supply. Even though the PSU would turn on (fans spinnin) but it gave no power. Hope this tip helps. If your PC doesn't boot the main culprit is the PSU and unseated RAM (push it firmly in).

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  • Alex

    Just built your $400 rig as I'm on a budget and it went swimmingly to start, got OS installed and all going than after several successful restarts I had to shut donw after updating graphics card driver, now It won't fire up, I checked all the power connectors and the main power from the PSU to the Motherboard seems to be the issue. When I start to insert it the power will flicker on, and at a certain angle it will stay on but plugging it in all the way fails to give any results. Is this a mobo problem, or possibly PSU, maybe just the connector needs replacing? components all brand new and I was not rough with anything while installing.

  • Alex

    Just built your $400 rig as I'm on a budget and it went swimmingly to start, got OS installed and all going than after several successful restarts I had to shut donw after updating graphics card driver, now It won't fire up, I checked all the power connectors and the main power from the PSU to the Motherboard seems to be the issue. When I start to insert it the power will flicker on, and at a certain angle it will stay on but plugging it in all the way fails to give any results. Is this a mobo problem, or possibly PSU, maybe just the connector needs replacing? components all brand new and I was not rough with anything while installing.

    • http://www.hardware-revolution.com/ MathieuB

      Alex,

      This is most likely a problem with your power supply connector. Get a RMA for your power supply and get it replaced. That should fix it up.

      Take care,
      Mathieu

    • http://www.facebook.com/AnnabellDarlienReedy Annabell Darliene Marrie

      I just built My first gaming rig, total was $897 dollars.
      I start it up… but I cant seem to figure out why my display wont work.. It will turn on, but It wont enter into Bios. Im literally stuck… Im going to check to see if My processor is loose. I’ll come back once I will see if this helps.

      • https://www.facebook.com/Mathieu.HR MathieuB

        If you’re using a dedicated video card, make sure that it’s fully seated in the PCI-Express 16x slot. That’s often the issue.

    • JayseFace

      I have the same problem as you, but I just leave the psu cord plugged in at that angle, otherwise it won’t turn on! I accidentally bumped my computer, just a tiny bit, and it shook the cord inside just enough to cause my computer to shut off and I had to open up the case and just moving the computer again caused it to turn back on. This is very inconvenient, but doesn’t happen often. To solve my curiosity, is the problem the PSU or the motherboard?

  • http://www.hardware-revolution.com/ MathieuB

    Alex,

    This is most likely a problem with your power supply connector. Get a RMA for your power supply and get it replaced. That should fix it up.

    Take care,
    Mathieu

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  • Danielco223

    Hi, I just built the 400 dollar rig as well. the computer powers up but I get no picture. Im not sure what the issue is. I have tried reinstalling the ram and the video card and tried different video connections. I also noticed that even though the picture on the monitor is not coming up, I get no power to the mouse and keyboard either. The case fan, cpu fan, and video card fan all run fine but there is nothing on the monitor.

  • Danielco223

    Hi, I just built the 400 dollar rig as well. the computer powers up but I get no picture. Im not sure what the issue is. I have tried reinstalling the ram and the video card and tried different video connections. I also noticed that even though the picture on the monitor is not coming up, I get no power to the mouse and keyboard either. The case fan, cpu fan, and video card fan all run fine but there is nothing on the monitor.

    • Danielco223

      I would like to add that I have not hooked up the PCIe power connector as there seemed to be no place for it to plug in.

      • Danielco223

        I would just like to say that I got the computer to work. Thanks so much for your awesome guide!

        • http://www.hardware-revolution.com/ MathieuB

          Danielco223,

          I'm glad to hear so, good job. I'm curious; what was the problem with your PC in the end?

  • Danielco223

    I would like to add that I have not hooked up the PCIe power connector as there seemed to be no place for it to plug in.

  • Danielco223

    I would just like to say that I got the computer to work. Thanks so much for your awesome guide!

  • http://www.hardware-revolution.com/ MathieuB

    Danielco223,

    I'm glad to hear so, good job. I'm curious; what was the problem with your PC in the end?

  • Csg_hze

    But what if it boots at first then it dies after a few mins/secs? :(

    • http://www.hardware-revolution.com/ MathieuB

      Csg_hze,

      Could you be a bit more specific by what you mean by dying? Does it freeze, randomly shutdown, what does it do exactly and when does it happen? The more details, the better.

      Also, what are the parts in your PC, that's something I'd need to know to help you out here.

      Take care,
      Mathieu

      • Csg_hze

        Thanks MathieuB but I got it sorted out, it was a faulty PSU. BTW the problem was that it kept turning on off on off on off non stop.

        • http://www.hardware-revolution.com/ MathieuB

          Csg_hze,

          I'm glad to hear that you got it sorted out. Faulty PSU makes sense
          considering the problem that you had. What was the PSU at fault, out of
          interest?

          In any case, enjoy your new working PC =)

          Cheers,
          Mathieu

  • Nabusharr

    Hi Mathieu,

    I bought all the recommended components for the $500 gaming pc build (no upgrades). All the fans come on including graphics card but no signal to monitor and no beep through the speaker. I have gone through the troubleshooting sequence described here and not been able to resolve, I would appreciate any additional support you could provide. No pins are bent and everyting is seated firmly. Thanks in advance for any help/guidance.

    Nabil

    • http://www.hardware-revolution.com/ MathieuB

      Nabil,

      Sounds like a defective motherboard to me. Return it for a replacement.

      Take care,
      Mathieu

  • Mrjelloman2010

    Hey I just built the 500$ dollar gaming rig, I have the 5750 and everything seems to turn on. But my hdtv doesn't detect the hdmi, is it possible that I have to just use dvi first and then setup hdmi compatibilities when i boot up a os?

    • http://www.hardware-revolution.com/ MathieuB

      Mrjelloman2010,

      Not entirely sure about HDMI, but it could be, I would try with DVI instead, DVI works for sure.

      If that doesn't work either, it means that your PC isn't booting, in which case I'd follow the steps listed in this post.

      Take care,
      Mathieu

      • Mrjelloman2010

        Well I tried to just breadboard it. Pretty much your lists and I got no post at all. I'm thinking the mobo so I issued an RMA.

        • http://www.hardware-revolution.com/ MathieuB

          Mrjelloman2010,

          Keep me updated on whether the new motherboard fixes up your issues or not. Also, make sure to install your RAM properly (See motherboard manual for the right slots to use), it's a common mistake, double-check power connections and the like.

          Take care,
          Mathieu

          • Mrjelloman2010

            Hey Mathieu! I got a new motherboard and when i first tried to breadboard it the psu and cpu fan would spin for 2 secs…So I used my friends power supply on the motherboard and everything started running? I went to seasonics site and they gave instructions on how to jump start the psu and so i did that and the psu fan kept spinning. But problem is when I plug it into the mobo…It does not work! Any advice?? Thanks!

            Zack

          • http://www.hardware-revolution.com/ MathieuB

            Zack,

            Sounds like your PSU works fine and the problem comes from somewhere else. Here's what to double-check/try:

            Are both the 24-pin and 4/8 pins power connectors plugged in the motherboard?
            Double-check for a short somewhere. Sounds like your motherboard is not grounded properly, which would explain the 2 seconds.

          • MrJelloman2010

            Hey I did what you said…The other PSU still works while the mobo is in the case. I'm not sure what to do. Is there a way to check for shorts on the PSU itself? If thats what you meant? Thanks again!

            Zack

          • http://www.hardware-revolution.com/ MathieuB

            Zack,

            So in short, it all works fine with the other PSU but not with yours? If that’s the case, return/exchange yours, it’s most likely defective/causing the problem.

            Take care,
            Mathieu

          • http://www.hardware-revolution.com/ MathieuB

            Zack,

            So in short, it all works fine with the other PSU but not with yours? If that's the case, return/exchange yours, it's most likely defective/causing the problem.

            Take care,
            Mathieu

  • Joe

    Having some interesting issues with the $1250 (previous) rig. Got it assembled with no problems, started it up on the first try, installed Windows, drivers, and updates. It was having some strange flickering issues where the screen would go black for about a second (still had a signal from the PC as far as I could tell, the monitor light was still blue) and come right back. The PC wasn't freezing, just losing video. And it only happened in the desktop (Chrome/IE specifically), never in game (where I assumed the video cards would flip out if they were going to).

    I went through and reseated all the components and installed a few more updates (BIOS flashing, full Windows 7 updates, etc) and the flicking issue appears to have abated. However, I have a new, far more frightening issue. The PC won't always power on. From the off position, I will hit the power button, and the PC will light up/fans start for about half a second, then shut off. It will continue to “try” to start up on it's own every 5-10 seconds or so if I don't unplug the PC or switch off the PSU with the same result.

    Eventually, it will boot properly. Sometimes, it will take 1-3 failed startup attempts, sometimes much, much more. I've gone through and disconnected all components in sequence to see what the culprit was and I was down to mobo, processor, and PSU only and still no startup. At this point I can only assume it's either the PSU, mobo, or processor. I've already set up an RMA for the PSU, but wanted to see if you had any additional thoughts or suggestions on what may be happening.

    Thanks so much!

    • http://www.hardware-revolution.com/ MathieuB

      Joe,

      Sorry for not getting to you earlier, your comment must have slipped by me or something.

      By the sound of your issues, it's most likely either:
      The PSU or the motherboard. See if the new PSU fixes the issue.

      If it doesn't, then I would look at the motherboard.

      Properly one of the two that got slightly damaged during shipping and that took a little while to manifest its defects.

      Let me know how this turns out.

      Take care,
      Mathieu

      • Joe

        Eventual success! The issue persisted after the new PSU arrived. I RMA'd both the video cards and motherboard for a refund, and ordered the new recommended motherboard and video cards. They worked great once I had them installed.

        Going to tidy up the cabling this weekend when I get a chance. Thanks for the reply!

        Joe

        • http://www.hardware-revolution.com/ MathieuB

          Joe,

          Glad to hear that you were able to resolve your PC problems in the end.

          Enjoy your new PC!

          Cheers,
          Mathieu

  • Shucklezzz

    Hey Mathieu,
    I recently was trying something out with my PC's(I have 2) and eventually just put them back together.

    Weird as hell, it has stopped working. Now see, my PSU is working properly and everything is connected for the most part which is why I don't understand. My computer was working PERFECTLY before hand. Now I have EVERYTHING connected the way it is suppose to be. I have tried every different combination for my RAM sticks, SATA inputs(There is 4, and I only have a CD and a Hard drive so I tried all those combinations), taking fans off, and putting the fans back on, taking out my GPU(HD 4850) out and just using the MB GPU, etc etc.

    Everything I try, it just doesn't show a picture on my monitor.

    Also, when I used to hold down my power button, it would shut down after 7-10 seconds of supressing it. Now when I try to do that, nothing happens and I would be holding it for minutes on end. The only way to shutdown the computer is to pull the actual power cable from the wall.

    Thanks ahead of time for the help. Hope you can get back quick.

    • http://www.hardware-revolution.com/ MathieuB

      I'd try putting it apart and see if it boots outside of the case with only the required components. If it does, be careful when you put it back within the case, its probably just a short somewhere.

      Otherwise, you might also have killed a part with static electricity unfortunately. Seeing as you have two PCs, try swapping parts from one to the other, to figure out the problematic part.

      • Shucklezzz

        Thanks a lot Mathieu.

        Apparently my CMOS was fried, and I had to go get a new one(It was like 4 years old).

  • dumbguy

    Hi Mathieu,

    I built the tier 1 gaming pc. The video card I changed to a radeon 5870, the psu into the corsair 750tx, and the hard drive into a 1tb, 6.0 gb/s seagate hard drive.

    I was so excited to play some games on this pc, this is the first one I ever built. But it won’t BOOT! The computer turns on, but the monitor doesn’t detect any signal. Like the fans and stuff works. I checked all the power connections. Still nothing.

    What should I do?

    Thanks you ahead of time for your help.

    • dumbguy

      nvm, i figured out whats wrong. apparently my cpu was loose

  • http://profiles.google.com/whiteknight5 Ravi Kulkarni

    I just built my pc and when i start it up everything seems to start up and i can get into bios, but then it goes to a black screen with a blinking white cursor in the top left and i can’t do anything else. I tried changing the boot order and booting with a win 7 install disk and a bootable usb, the optical drive seems to spin up on start up and then spins down and i get the same black screen with blinking cursor.

    Any ideas as to what could be causing this?

    Thanks in advance!

    • Mike

      I’m getting the same issue, did you ever resolve this?

      • Mike

        fixed it, I was installing ubuntu and the disk was bad.

  • Andreighiu

    I recently bought a new computer with MB Asus P7P55D-E Pro i7 870, Nvidia 460 GTX 768 MB graphic card, and now i have troubleshooting with turn on this system, i get no signal on monitor and when i try to put both 6 pins connectors on VGA the system don’t turn on, with only 1 connector the mb starts but the vga led lights because it’s not enough power to powerup VGA, my question is from your point of view, which is the main problem, MB, PSU or VGA?, thank you in advance!

  • InkredibleKev

    my new rig (first build attempt ever) I cant get to the bios screen, nor can i get my display to recognize my gpu.

    sabertooth p67 mobo
    i5 2500k 3.3Ghz. cpu    (stock cooler, i don’t plan to overclock)
    gskill ripjaw ddr3 1066 pc8500 4gb x 2 (8gb)
    rosewill green 630w psu
    Nvidia GTX 560 ti
    WD 500GB HDD 7200rpm
    LG Blu Ray drive (i know this works, it’s from my old pc)

    the cpu is in correctly, ram is all the way down in the white slots. tried one stick at a time.
    24 pin is connected, 8 pin is connected for the cpu. power goes through the mobo, the case fans spin, the gpu fan spins, the speaker doesn’t make any beeps though and it appears like my monitor doesn’t recognize the gpu. no bent pins on mobo and again, cpu is in correctly. please help. i would like to make my stuff work.

  • Gwendolynne Simeone

    We keep getting a message:
    PXE-E61: media test failure, check cable
    PXE-M0F: exiting Intel boot agent

    Reboot and Select proper Boot device or insert Boot Media in selected boot device and press a key

    We have no idea what to do since we’ve gone over the wires a few times and are just stuck. Can you help maybe?

    • http://www.facebook.com/AnnabellDarlienReedy Annabell Darliene Marrie

      It’s Most likely Your graphic’s card. I Encountered the same problem.

  • Rtutino

    i have my gpu cpu ram and motherboard plus the case all attached would the fans and leds turn on or do i have to install the hard drive and cd drive to have it all working for fans and leds to start 

    • Rtutino

      also i have the psu

  • http://twitter.com/trexasaurusman John Jevitz

    Just built a pc, every time I turn on the power it turns on, then quickly turns off. What’s up?

    • http://www.facebook.com/AnnabellDarlienReedy Annabell Darliene Marrie

      I had the same issue with my Alienware Aura first gen. It’s probably, your motherboard. I had to replace mine, It did the same thing.

  • MM2012

    I just recently built one of the workstation setups you have listed, components i7 3820, as rock x79 extreme 6, pny quadro 2000, san disk 240 gb ssd, seasonic m12ll 620w PS, asus 24x dvd drive, arctic i30 cooler, and the memory i used was the optional 32 gb komputerbay set. when i turn on the MB with just processor I get the 3 long beeps and a code 19 followed by a code 53 on dr debug display, as soon as I add the memory in any quantity ( 1 stick, 2 sticks all 4 sticks ) when power on I get no beeps and dr debug flashes a 60 code then a 61 code and just sits at the 61 code. In the manual this code means nvram initialization. My question is what exactly does this mean? I have tried to find info on this condition/code but no luck. I had the system fully built and it would not post, no output from video card or anything past freezing at the code 61. Is this memory for some reason not supported or is there an issue with the MB? This is my first system build from ground up, I do have some experience with component upgrades/ replacements and also fresh HDD/os installs but not sure the next steps for this issue.

  • TestMaster

    very helpful .Without this I would have stuck my projects.
    thanks a lot.Keep it up and share more and more knowldge please.

  • suhail bota

    hey all. I just built a new pc. all brand new parts but as I turned it on for the first time it beeped 4 times and won’t show anything on screen. any advice or sokutions?

    • MR

      might be wrong RAM placed

  • Amy

    I need help guys! I’ve been trying to set up my new computer FOR DAYS!!. I bought all brand new gear to go inside my old shell. I didn’t buy a graphics card as the motherboard has a sufficient one on it for now. First attempt failed because the power supply was faff so replaced it. I now have the pc up and running but it will not boot up. I get messages like insert manufacturers disk into A drive…I have no a drive and havn’t been given a disk. It will not recognise the hard drive but the hard drive is in tact because I tried it on another computer. We are at a loss as what to do!! Please help if you can guys I’ve been trying to play a game for 4 days and need a break….nothing seems to be going right :( xx

  • dale

    just bought a new rig mother board a55m-ds2,processore a63500 the pc wont on no sounds,beep even the fan ive check psu but the psu is okay what may have the problem???

  • Matias

    i bought and put together my own desktop. but when i turn it on i cant get past a set up screen in guesing. It says “Driver disk Preparer v1.07 ASRock incorporation, all rights reserved Model name: H77M

    Generate serial ATA Drive diskette? [y/n]” when i click y it then says..
    “source: Generate serial ATA Driver diskette
    No supported drive found: floppy 1.44MB and USB drive!
    Reboot system now
    Press any key to continue..” i cant get past this i keep getting this screen what does it mean?? what do i do):
    plzzz help

  • eskimopie77

    i had this same problem when building mine… turned out to be the microprocessor i bought was faulty

  • Darren Miller

    If anyone could help me I would be so happy!

    My mums pc decided to no longer power on, whenever I pressed the power button the fan spun for half a second and cut out. I did the magical paperclip test on the psu and it worked fine so it was looking like a motherboard fault.
    I got a new motherboard and put everything in plugged it in and pressed the button…nothing! I heard of the jump start on the power switch connectors and boom it booted up! Connected the power switch connector and manahed to turn the pc off. All was working well again.
    I thought to myself great thats probably what wss the problem all along. Took new board out put old board in and tried the jump start. ..nothing. not even a flicker of power. So I put the new board back in and nothing. Now this new board womt even work.
    Did I do something wrong?
    What should I do?

    Thank you for any replies in advance