September 14, 2009 | Comments Comments

Warning: These P55 motherboards will cripple your Crossfire/SLI performance

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By Picture Perfect Pose

By Picture Perfect Pose

The release of Core i5 and i7 Lynnfield also meant the release of various motherboards with all one thing in common: The socket 1156.

If you look at the pictures of motherboards, you would believe that they are all at least equipped with two PCI-Express 16X ports. Let me explain where you might get fooled though.

What are you talking about?!

In order to cut on costs, on fourteen different motherboards, the second PCI-Express 16x is not connected via 8 lines to the PCI-Express controller of the LGA1156 processor (The first port then also being at 8x), but rather with 4 lines on the P55 controller.

On top of that, while the lines connected to the LGA1156 processor work at 5GT/s, the ones connected to the P55 only work at 2.5GT/s.

This result in a bandwidth of 1Gb/s in each direction for a PCI-Express 16x slot working at 4X with the P55 chipset, as opposed to 4GB/s when it’s working at 8x with the processor!

Needless to say, running Crossfire or SLI on a motherboard equipped with a 16x that works at 4x and is connected to the P55 chipset will cripple your performances.

Thank you to Hardware.fr (French website. I enjoy being bilingual :) ) for reporting this.

The list of motherboards to avoid if you want to use Crossfire or SLI

Here’s a list of motherboards whose second PCI-Express slot is connected at 4X with the P55 and that I urge you to avoid if you plan to build a Crossfire or SLI system:

Asrock P55 Pro
Asrock P55M Pro

Asus  P7P55D
Asus P7P55D Evo
Asus P7P55D LE

Evga P55 LE
Evga P55 Micro LE

Gigabyte GA-P55M-UD2
Gigabyte GA-P55-UD3
Gigabyte GA-P55-UD3L
Gigabyte GA-P55-UD3P
Gigabyte GA-P55-UD3R
Gigabyte GA-P55-US3L

MSI P55M-GD45

The list of motherboards to go with if you want to use Crossfire or SLI

Here’s a list of motherboards that will not cripple your performance and run your video cards at 8X/8X with the LGA1156 processor controller. Note that no card needs 16X bandwidth yet, not even three Geforce GTX285 in Three-Way SLI.

They all support Crossfire and I indicate whether they support SLI or not.
I included a link to either NewEgg or Amazon when I could find them in stock at any of the two online stores.

ASRock P55 Deluxe (Two-Way SLI)
Asrock P55 Extreme (Two-Way SLI)

ASUS Maximus III Formula (Two-Way SLI)
Asus Maximus III Gene (Two-Way SLI)
ASUS P7P55 WS SuperComputer (Three-Way SLI, equipped with NF200)
ASUS P7P55D Deluxe (Two-Way SLI)
Asus P7P55D Premium (Two-Way SLI)
ASUS P7P55D PRO (Two-Way SLI)

BIOSTAR T5 XE (No SLI)
Biostar T5 XE CFX-SLI (Two-Way SLI)
BIOSTAR TPOWER i55 (Two-Way SLI)

Evga P55 (Two-Way SLI)
Evga P55 Classified 200 (Three-Way SLI)
EVGA P55 FTW (Two-Way SLI)
Evga P55 FTW 200 (Three-Way SLI)
EVGA P55 Micro (Two-Way SLI)
GIGABYTE GA-P55M-UD4
Gigabyte GA-P55-UD4
GIGABYTE GA-P55-UD4P
GIGABYTE GA-P55-UD5
GIGABYTE GA-P55-UD6

Intel DP55KG
Intel DP55SB
Intel DP55WB
Intel DP55WG

MSI P55-GD65
MSI P55-GD80

Conclusion

If you have a blog, a website, Twitter account, Facebook, etc., I would deeply appreciate if you link to this story and spread the news. I would hate to see people buy a P55 motherboard without knowing this. I’m sure that you’ll agree ;)

I wish that manufacturers would make it more clear, but then again, it is up to the customer to double-check every information before making a purchase

As always, make sure to read all the specifications before buying any part and in the case that you have a doubt, consult with experts ;)

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  • Marcos
    Great article, Mathieu. I'm looking to build an inexpensive gaming pc with the i5 processor. I'm glad I have you on facebook.
  • Brandon
    Hm, if this is an issue, other sites will start to report the same. Lets see how this plays out.
  • BC Mack
    Are you seriously dense? You completely ignored the technical specs of the new processors. 1156-based Core i5s and i7s have a built-in 16-lane PCI-E controller, which means no matter what you choose to run in Crossfire/SLI it will run slower - dual cards at 8x each, three cards at 6x, and so on.

    You're also completely over-hyping this by picking out all the budget boards and claiming they falsely advertise. First off, they're not advertising anything. Go look at the pics of the packaging or the boards themselves - nowhere does it say the second slot is full 16x, and in some cases it's clearly marked "will run in 4x mode". Also, you completely ignore the fact that budget boards like these have been on the market for years with multiple 16x slots that run in less than 16x mode - they just had a Socket 775 or AM2.

    I'd say it's clear that you need to sit down and learn something about new tech when it comes to market before you start telling people not to buy something. Or, at the very least, don't even bother looking at products priced for budget gamers/enthusiasts.
  • Mathieu
    BC Mark,

    You make me wonder if you read the whole article.

    I'm well aware that the processors based on the LGA1156 socket are equipped with a 16-lane PCI-E controller, that is something that was made very clear by Intel.

    Where do you get that it will run slower at 8X? I included this link from HotHardware in the article: http://hothardware.com/Articles/Asus-P6T6-WS-Re...

    Where they benchmark three Geforce GTX 285 in Three-Way SLI and they compare 16x/16x/16x vs 16x/8x/8x and they found NO difference in performance what so ever.

    Obviously, we are talking about PCI-Express 2.0 here, not 1.0.

    Regarding advertising. No where in this article do I state that motherboards manufacturers are doing false advertisement.

    I simply say that if someone was not to pay attention to specs when buying a motherboard, they might not get the best performance out of Crossfire or SLI.

    I also say at the end that I wish that it made more clear, like with Intel who used shorter PCI-Express slots length on their motherboards to show that they are not 16X slots.

    As for ignoring that budget boards have been like this for years, I simply don't agree with you, as this is a different situation in my opinion.

    I know quite a few persons who expected to see 8X/8X on any motherboard equipped with two slots, due the design of the LGA1156 processors. Clearly, this is NOT the case and this is why I'm reporting it.

    Besides, the "4X mode" is much slower than a 4X connected to the LGA1156 processor is, as I pointed in my article.

    My goal here was simply make sure that this is clear for anyone who intends to buy a P55 motherboard. There's a pretty wide audience, with a varying levels of knowledge. I believe that this article was useful to many. You have the right to not agree though.
  • Kurt
    Great article. Even though some misunderstood what you were saying (and quite frankly, just want to pretend they are smarter than you), I think you were writing this for people who may be in the market but don't know what specs are important so they may end up with something that will impose limits on their hardware.

    Since I have been looking at these boards myself, I agree that not all manufacturers are as outright about the limitations as they should be. They will advertise 3-way SLI but unless you get into the specs and see the 8x, 4x, 4x you would never know that they are talking about reduced throughput.

    My question for you is... given the choices available, which is the best board for Crossfire (16x, 16x) with two ATI video cards and an LGA1156 with i7 processor? I don't want to give up performance and I want lots of retro-tech included (I just got over AGP). Also looking at a price cap of around $300.00.

    Thanks!
  • Mathieu
    Kurt,

    You're right on regarding who I targeted with this article.

    The problem I believe is not so much that manufacturers are not outright about limitations, but rather that many people believe that if you have two PCI-Express slots and that the box says "Crossfire supported", they have everything that they need. Most people won't dig deeper due to their lack of knowledge. Then again, there isn't that much information available either.

    Regarding the best board for Crossfire. First of all, there are no 16x, 16x boards, as the processor has a 16 lanes PCI-Express controllers, so that's 8x, 8x for two cards in Crossfire.

    That said, my personnal choice would the ASUS P7P55D Pro which you can find here: http://bit.ly/3Hzj2w

    It features a very good layout, as you can actually use a PCI slot if you have a PCI controller card or sound card, two PCI-Express 1x slots for additional add-on cards. On the back, you have two PS/2 ports for older mouse and keyboards, 8 USB ports, e-SATA, Firewire and RJ-45 (LAN), along with Coaxial and Optical S/PDIF out and finally 8 channels audio.

    Also good to know, you have a IDE and a floppy port on this motherboard, two older ports that are starting to disappear on some motherboards.

    Best of all, it's priced at $169.99!

    I believe that it offers a very nice balance of features, a great layout and ASUS is the most trusted brand by readers here on Hardware Revolution, for a good reason.

    Hope that helps you out.
  • Woody
    There is no deception here. The specs for these systems are published. These motherboards are designed for budget to mid range systems at best so their performance is more in line with what the consumer would need for the price they want. Dropping two or three very high end and expensive graphics cards into an LGA 1156 based motherboard would be silly so there is no need for more bandwidth. That is why Intel has the LGA 1366 systems. For mid range graphics cards there is more than enough bandwidth for SLI or crossfire which is what these boards are designed for.

    In my opinion the original article is misleading and indicates a lack of technical understanding on the part of the author. Sorry about that but you should do your research before you cut loose online.
  • Jay
    BIOSTAR T5 XE does not support 8x/8x, says the specs.

    Thanks for the article though, quick resource to find CF/SLI boards.
  • sam
    is the p7p55d motherboard that supports crossfire really such a bad choice for for future crossfiring. i understant that instead of getting 8x 8x i would get 8x 4x. is that like only getting half of the peformance that i am paying for for the other card runnibg at 4x or am i understanding the concept wrong.
  • Sam,

    Yes, any of the motherboards that are set up in such a way are to avoid for Crossfire, especially in the future.

    The lines connected to the LGA1156 processor work at 5GT/s while the ones connected to the P55 only work at 2.5GT/s. Meaning that instead of 8x 8x, you would get more like 8x 2x.

    Anything under 8x will bottleneck a current generation video card.

    Hope that helps.
  • RogerWilcoZA
    Hey Mathieu, great article. I'm no techie so apologies to all if this is a silly question.

    I'm about to buy a new system using the Asus P7P55D board and a single HD 5850 card. However I'm also going to be purchasing a Asus Xonar soundcard which will go into the unused 1x PCI express slot. Would this affect the bandwidth of my video card?
  • Hey Roger,

    No problem about not being a techie, this blog is open to everyone, beginners or experts. After all, we all start somewhere.

    The video card is linked directly to the CPU, while the sound card will be linked to the chipset, so to answer your question, no this will not affect the bandwidth of your video card.

    Hope that helps.
  • RogerWilcoZA
    awesome nice one
  • CJ
    DFI p55 mobo runs at 16x or 8x/8x or 8x/8x/4x. It will not cripple your sli setup. Take DFI's name out of that list.
  • After verification, the DFI Lanparty DK P55-T3eH9 runs either at 16x/4x/none or 8x/4x/8x. Thanks for pointing it out, it has been taken off the list.
  • Carrot
    Thank you - it's a shame, I bought a pre-built iBuypower PC and it didn't say the chipset mobo it came with was this model. So I'm stuck with a setup I'd like to do SLI on, that says is SLI ready, when in fact, it's not.

    Guess I need to look at upgrading... grr. So frustrating.
  • Rayden47
    Mathieu,

    Thanx for all the hard work u 've put to help us guys. I've done much research on motherboards, cpu, graphics cards and monitors, but never came through this blog until today. And I think u are actually the person we can rely on. Keep up the good work.

    I m planning to build a gaming pc within $1500 (Rs.60,000 INR). So please suggest me a configuration. My priorities are Intel i7 860, ASUS/MSI P55 MoBo supporting Crossfire and SLI, and Good 22" LCD monitor for gaming. And please tell me What do you think about Intel i7 860 CPU?
  • Pick
    Asrock P55 Extreme is also a 16x/4x performance crippler, you should take it off your list. Anyways, good lookin'! :)

    Pick
  • Pick
    Sorry, I was mistaken there - seems the Asrock P55 Extreme is indeed an 8x/8x mobo. Please delete my posts, if possible...
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