A mistake seen too often by myself and other experienced computer builds is someone who’s trying to save a few dollars by getting a cheap power supply, only to hear from them later on about having troubles with their computer such as it not starting, freezing, random rebooting, or worse, having the power supply take down a few parts if not the entire computer system by blowing up.
The power supply is responsible for delivering constant stable power, preventing the current from fluctuating too much and protecting your computer from power surges and other electric dangers.
Skipping on your power supply only to save a few dollars is a recipe for disaster sooner or later.
In this article, I will give you detailed explainations on how to avoid the 6 Surefire Ways of Blowing Up Your Computer Due to an Inadequate Power Supply and I’ll end it with a list of The Best Power Supplies For Your Money.
- Buying a Power Supply that Cannot Deliver Enough Power
- How much power do I need?
- Buying a Power Supply that Cannot Deliver Enough Amps on the 12V Line
- Electricity 101: The Differences between Voltage, Current and Resistance.
- How does this apply to a Computer?
- Ok. Where’s the problem?
- Simple or Multiple 12V Lines (Rails)?
- How to find out the real total amount of Amperes that a power supply with multiple 12V Lines can actually deliver
- Confusing Marketing Tricks
- Choosing a no-name or low-quality brand power supply
- The difference between a no-name/low-quality and an high-quality power supply
- Detailed explanation of what is PFC
- The Watts Rating for a Computer may not be equal to the VA Rating.
- Brands to avoid
- My Top 10 Brands that I recommend
- What about this other brand?
- Not Considering the extra power requirements of Overclocking
- Not Considering How Many Connectors you Need Now and Not Planning Possible Parts Upgrades Down the road
- Making Sure You Have Enough Connectors for All Your Parts
- Planning Possible Parts Upgrades Down the Road
- A Power Supply with Poor Efficiency
- While your computer won’t explode due to a power supply with poor efficiency, your electric bill will!
- 80 PLUS Certified
- Bonus Point: The Best Power Supplies For Your Money
1. Buying a Power Supply that Cannot Deliver Enough Power
For your computer to function properly, your power supply has to be able to deliver enough power to your components. The number 1 point in this article is power, measured in Watts (W).
How much power do I need?
It’s impossible for me to give you a single answer, as everyone have different computer systems with different power requirements. To answer this question, I recommend that you use the following power supply calculator:
Enter the parts that you use, or intend to use and indicate whether you intend to overclock or not.
Add 100 Watts to your results
Once you have a number, I recommend that you add up 100W to your result.
For example, I get 402W out of the eXtreme calculator, for my own overclocked system. In this case, I’d recommend getting at least a 500W power supply.
Why? Because you don’t want your power supply to run too close to its maximum output, as that will shorten its lifespan, make it less efficient (costing you more on the electricity bill and generating more heat). Also because the power supply calculator isn’t perfect and you rather want to be on the safe side with those much power than on the dangerous side with a power supply too close to its maximum capacity.
Keep in mind that overclocking increases your power requirements. l’ll go in details about this in point #4.
Alright Mathieu, I know how many Watts I need, can I buy this (Insert Number) Watts power supply from x brand?
No, not yet. Remember the title of this article? Warning: 6 Surefire ways of blowing your computer due to an Inadequate power supply.
Watts are only the first point, you have five more points to go through. Now that you know how many Watts you need, let’s move on to point #2.
2- Buying a Power Supply that Cannot Deliver Enough Amps on the 12V line
As much as the power (Watts) requirement matters, the current requirement, measured in Amps is as important if not even more important. This is especially true if you have a or several dedicated video card(s). As a general rule of thumb, you’re aiming for the highest number on the 12V line.
What? Now I have Watts, Amps and 12V line?! This is way too confusing!
Fair enough. Let me explain this in plain English with a very simplified electricity 101 course:
Electricity 101: The Differences between Voltage, Current and Resistance.
Three of the most basic units in electricity are Voltage (Measured in Volts) and Current (Measured in Amps) and Resistance (Measured in ohms).
A neat analogy to help you understand these terms is a system of plumbing pipes. The voltage is equivalent to the water pressure, the current is equivalent to the flow rate, and the resistance is like the pipe size.
There is a basic equation in electrical engineering (I = V/r) that states how the three terms relate. It says that the current is equal to the voltage divided by the resistance.
Thanks to HowStuffWorks for the information. For more information on this, visit their article here.
How does this apply to a Computer?
For a computer system, you need enough power (Watts). Different components in a computer need different voltage, such as 3.3V, 5V and 12V, among others. For your system to work properly, your supply has to be able to deliver enough power flow, in Amps (Amps = Watts divided by Voltage) to every part.
Now, in the recent years, the demand on the 12V line, used for the Processor and Video Card(s) have been increasing as these parts have become more powerful and demanding more and more power.
Ok. Where’s the problem?
A lot of cheap or poorly designed power supplies will be able to deliver enough power (Watts) but not enough power flow (Amps) to the components for them to function properly, resulting in your computer not booting up, freezing, crashing, randomly restarting, etc.
This is why the Amps ratings are as important as the Watts rating on a power supply. You do not want to overlook that.
Single or Multiple 12v lines?
There’s also the debate about using a power supply with a single or multiple 12V lines.
How do you figure out which one of the two a particular model is?
See the following pictures, which I’ll use for a comparison at the same.
Both power supplies are rated for a maximum of 600W power output in total overall.
Can you spot the difference? On the OCZ model on the bottom, with multiple 12V rails, you have +12V1, +12V2, +12V3 and +12V4, each one rated for 18A.
On the Xanity model on the top, with the single 12V rail, you simply have a +12V, rated for 37A.
You’re probably telling yourself that the OCZ model, on the left, has more much potential, with 72A in total by combining the four 12V rails!
Not quite. See, the thing that the marketing folks don’t tell you is that each of those multiple rails can deliver up to 18A, but they cannot do it all at the same time.
How to find out the real total amount of Amps that a power supply with multiple 12V Lines can actually deliver
A good trend that I’m starting to see in the last year or two is that manufacturers are actually starting to write how many Amps all the 12v lines can deliver together, like the example on the right.
How do I find the Amps rating if all I have is the maximum amount of Watts all the 12V lines can deliver together?
Simply divide the Watts rating by 12 to get the Amps rating, based on the following formula: Amps = Watts / Volts.
How to estimate the total of Amperes that multiple rails can deliver if you don’t have the maximum amount of Watts all the 12V lines can deliver together?
Going back to the OCZ600SXS example from one of the pictures above, To find the true total of Amperes that those 12V lines can deliver together, here are some maths for you:
The maximum combined rated wattage for the 3.3V, 5V and all the 12V lines is 580W. In the markerting world (read: In a dream world) where the 3.3V and 5V don’t use any power you’d have 580W available in total, to be separated between all the 12V lines.
580W / 12V = 48.33A. That’s the maximum amount of 12V amps that the power supply would be able to supply in an unrealistic situation.
Now, back to real life, let’s assume that the 3.3V(@10A=33W) and 5V(@10A=50W) used 88W. This is a guess, not too far from real usages though, which varies depending on your setup of course. In this assumption, that means that the 12V lines would have 492W now.
492W / 12V = 41A.
Confusing Marketing Tricks
In both cases(48.33A or 41A), that’s far from the 72A you would have first thought of right? Over 40% off what you would have thought in the second case! Imagine buying a car only to discover that it offers more than 40% less power than you thought, because of confusing marketing tricks. You would be pissed right?
So this goes to show you that you have to be careful with multiple 12V rails power supply for that. Marketing makes it look like this particular power supply from OCZ does deliver up to 72A on the 12V lines, because anyone could easy conclude that by adding up the 4 lines amps together.
3. Choosing a no-name or low-quality brand power supply
The differences between a no-name/low-quality and a high-quality power supply
A high-quality power supply is equipped with higher quality components that protects your computer from a variety of risks. It will also be equipped with safety circuitry to prevent damage resulting from short circuits, over current and over voltage.
A cheap or low-quality power supply is not equipped qith such safety features and will let your computer take the damage resulting from electric dangers!
Most important, high-quality power supplies are equipped with PFC (Power Factor Corrected) meaning that they can actually output the power that they are rated for. What do I mean by that? Read more below:
Detailed explanation on what is PFC:
The power drawn by computing equipment is expressed in Watts or Volt-Amps (VA). The power in Watts is the real power drawn by the equipment. Volt-Amps are called the “apparent power” and are the product of the voltage applied to the equipment times the current drawn by the equipment. Both Watt and VA ratings have a use and purpose. The Watt rating determines the actual power purchased from the utility company and the heat loading generated by the equipment. The VA rating is used for sizing wiring and circuit breakers.
The VA and Watt ratings for some types of electrical loads, like incandescent light bulbs, are identical. However, for computer equipment the Watt and VA ratings can differ significantly, with the VA rating always being equal to or larger than the Watt rating. The ratio of the Watt to VA rating is called the “Power Factor” and is expressed either as a number (i.e. 0.7) or a percentage (i.e. 70%).
The Watt rating for a computer may not be equal to the VA rating!
All Information Technology equipment including computers uses an electronic switching power supply. There are two basic types of computer switching power supplies, which are called 1) Power Factor Corrected supplies or 2) Capacitor Input supplies. It is not possible to tell which kind of power supply is used by inspection of the equipment, and this information is not commonly provided in equipment specifications.
Power Factor Corrected or PFC supplies were introduced in the mid 1990’s and have the characteristic that the Watt and VA ratings are equal (power factor of 0.99 to 1.0). Capacitor Input supplies have the characteristic that the Watt rating is in the range of .55 to .75 times the VA rating (power factor of 0.55 to 0.75).
(Thank you for this information, which comes from White Paper # 15, from Neil Rasmussen at APC. If you want more details on the difference between Watts and Volt-Amps, on power supplies and PFC, you can read the integral version of the White Paper #15 here. Note that it’s a Pdf Document, so you need Abode Reader installed on your computer to open it.)
Brands to avoid:
- A-TOP Technology
- APEX (SUPERCASE/ALLIED)
- Aspire(Turbo Case)
- Athena Power
- Broadway Com Corp
- Dynapower USA
- FSP Everest
- HEC Orion
- Hiper Type-R
- I-Star Computer Co. Ltd
- In Win
- JPAC COMPUTER
- Just PC
- Kingwin Inc.
- Linkworld Electronics
- Logisys Computer
- Norwood Micro/ CompUSA
- Spire Coolers
- Star Micro
- Thermaltake Purepower NP
- Thermaltake TR2
- TOPOWER TOP
- Ultra X-Connect
- Ultra X2 >700watts
My Top 10 Recommended Brands
- Antec: Avoid any EarthWatts models over 700W, but the rest of Antec power supplies are recommended.
- Cooler Master: Avoid their eXtreme series but the rest of Cooler Master power supplies are recommended.
- PC Power and Cooling
- RoseWill: Only their Xtreme/RX series. Avoid other series.
- Thermaltake: Only their Purepower and Toughpower series. Avoid other series.
Thanks to folks at EggXpert and their Tiered Power Supply List that has been of great help for this section.
4. Not Considering the Extra Power Requirements of Overclocking
Overclocking, or raising a part (CPU, Video Card, RAM) frequency beyond the manufacturer set frequency to gain extra performance, is a strain for a power supply. If you overclock, it is even more important to have a high-quality power supply that can handle the extra load.
As the frequency increase, so does the power consumed by the overclocked part. If you raise the voltage, the power consumption goes up even more, putting even more stress on your power supply. How much is hard to quantify, as every CPU and video card have different power requirements. However, it is not rare to see the power consumption go up by 50W, 100W, 150W or even more, depending on your computer setup.
I simply recommend that if you overclock, make sure that your power supply is powerful enough to handle the extra load. If you have a cheap power supply or are already close to its limit, do not overclock as you’re putting your power supply and possibly your computer on the line!
5. Not Considering How Many Connectors You Need Now and Not Planning Possible Parts Upgrades Down the Road
So, you know how many watts you need, you keep a close eye on the Amps rating, have chosen a good brand and have taken in consideration overclocking (or no overclocking).
Making Sure You Have Enough Connectors for All your Parts
Now, you have to make sure that you have enough connectors for everything and that they are long enough.
Every power supply comes with a 20+4 (or 24) pin ATX connector and a 4/8 pin 12V connector, that both connect in the motherboard.
Video Cards will need either one or 6-pin PCI-Express connector, one 8-pin or a mix of the two. Needless to say, if you have 2,3 or 4 video cards, make sure to get a power supply with enough connectors.
Then you have hard drives, optical drives that use either SATA or Molex 4-pin connectors and fans that use molex connectors. Once again, make sure you have enough connectors.
Planning Possible Parts Upgrades Down the Road
Knowing that a good power supply can last you many years, you want to think about possible upgrades to your computer system in the future, to make sure that your power supply can handle the load with that new part.
For example, if you choose to go with an on-board video card for now, but decide to upgrade to an high-end video card, which can easily draw 150-200W alone, you want to make sure to consider that when you’re planning your power supply purchase.
Otherwise, your computer won’t boot, will freeze, reboot randomly or in the worse case scenario, your power supply will give up with a bang, literally. In the process, it might fry one or several parts in your computer too. You wouldn’t be happy if your brand new $200 video card gets kill because of an inadequate power supply now, would you?
6. A Power Supply with Poor Efficiency
One of the power supply jobs is the convert current from AC (From your outlet) to DC (To your Computer Parts). This is not a perfect process and some energy is lost in the process, in the form of heat.
A power supply efficiency, on average, can be as low as 60% or as high as 90%.
While your computer won’t explode due to a power supply with poor efficiency, your electric bill will!
Let’s do some maths here to compare a 70% efficient power supply and a 85% efficient one, two efficiency level commonly found in computer power supplies.
Let’s assume that your electricity cost is $0.15 per KW/h, that you use your computer ten hours per day and that it consumes on average 500W (High-end Gaming PC in gameplay for example).
A power supply with an efficiency of 70% will use about 710W to output 500W. while a power supply with an efficiency of 85% will use about 590W to output 500W, for a difference of 120W between 70% and 85% efficiency.
120W x 10 hours = 1200W per day. 1200W per day x 365 days = 438,000 Watts more per year.
Now, your bill is in KW, so 438,000 / 1000 = 438 KW.
Now, multiply the KW with the cost by KW/H 438 x $0.15 = $65.70
That’s the difference in cost for your electricity bill after one year. In this example, using a less expensive but less efficient power supply will cost $65.70 per year more compared to the power supply with 85% efficiency.
80 PLUS certified:
Power Supplies that are certified 80 PLUS have been independently tested for their efficiency. Now, there are 4 different 80 PLUS certifications, depending on how efficient the power supply is:
80 PLUS: The power supply is at least 80% efficient at 20%,50% and 100% load
80 PLUS Bronze: The power is at least 82% efficient at 20% and 100% and 85% efficient at 50% load.
80 PLUS Silver: The power is at least 85% efficient at 20% and 100% and 88% efficient at 50% load.
80 PLUS Gold: The power is at least 87% efficient at 20% and 100% and 90% efficient at 50% load.
The 80 PLUS and highercertifications are the way to go when you are looking for an efficient power supply.
Do not trust specifications such as “Efficiency: 80% to 85% Efficiency Typical” that are not 80PLUS certified. 80 PLUS is an independent standard test. No 80 PLUS and “Efficiency: 80% to 85% Efficiency Typical” means that it is 80% to 85% efficient, according to the manufacturer that is, using their own in-house test, which may or may not so much represent real efficiency.
7. Bonus Point: The Best Power Supplies For Your Money
By that, I mean the power supplies that offer the best features at a given price. Why would you want that, you ask?
Because you want the best possible power supply for your hard-earned money!
If you have the time, reading detailed power suppliy reviews and specs are a lot of fun. However, most of us don’t have the time to do the research and just want the answers. In other words, what you want to know is what is the best power supplies within your budget.
So if you don’t have the time to do the research, or just don’t care to do it, don’t worry. I’ll come to your help with this guide of the best power supplies for your money.
Keep in mind:
I’ll use this opportunity to remind you that this article is only a guideline for the prices I’ve seen on November 27th. You’re letting yourself down if you’re not looking for deals when you decide to purchase.
Keep in mind this when you read this list: This list is based on the best U.S. prices from NewEis. Prices and availability change everyday. I can’t keep up with accurate pricing everyday, but I can suggest to you great power supplies that you won’t regret buying at the price ranges that I list.
Best Power Supply for ~$50: CORSAIR CMPSU-400CX 400W PLUS Certified
Best Power Supply for ~$75: Antec EarthWatts EA650 650W 80 PLUS Certified
Best Power Supply for ~$100: Antec TruePower New TP-750 Blue 750W 80 PLUS BRONZE Certified
Great Alternatives at $100:
Best Power Supply for ~$125: Seventeam ST-850PAF 850W 80 PLUS BRONZE Certified
Great Alternatives at $125:
- Antec CP-850 850W 80 PLUS Certified
- SILVERSTONE ELEMENT ST75EF 750W 80 PLUS BRONZE Certified
- Antec TruePower New TP-750 750W 80 PLUS BRONZE Certified
Best Power Supply for ~$150: CORSAIR TX Series CMPSU-950TX 950W 80 PLUS BRONZE Certified
Great Alternatives at $150:
Best Power Supply for ~$200: SeaSonic X750 750W 80 PLUS GOLD Certified
Great Alternatives at $200:
- CORSAIR CMPSU-850HX 850W 80 PLUS SILVER Certified
- SeaSonic M12D SS-850 850W 80 PLUS SILVER Certified
- CORSAIR CMPSU-1000HX 1000W 80 PLUS Certified
Best Power Supply for $300: Antec TPQ-1200 1200W 80 PLUS SILVER Certified
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