Sign in with
Sign up | Sign in
Your question

Mobo for crossfire HD 7970 16x16x8?

Last response: in Graphics & Displays
Share
February 2, 2012 1:57:29 PM

Hey guys, looking to include a Radeon HD 7970 in the new build but having trouble picking a mobo. Looking to run a crossfire setup but not sure whether i should pony up the extra cash for a mobo with 16x16x8 pcie configuration or if i can get away with a 16x8x8 pci config. When looking at the Toms benchmarks for the Hd 7970 crossfire they used a Gigabyte z68 board with a 16x8x8 configuration. I was surprised at this so I'm thinking i can get away with the same, I just don't want to bottleneck the cards as you know running in a 16x8x8 will default both cards to running at 8x.

Also if your insisting on a 16x16x8 config can you recommend a well priced board.

Cheers
February 2, 2012 2:02:04 PM

binderjeep said:
Hey guys, looking to include a Radeon HD 7970 in the new build but having trouble picking a mobo. Looking to run a crossfire setup but not sure whether i should pony up the extra cash for a mobo with 16x16x8 pcie configuration or if i can get away with a 16x8x8 pci config. When looking at the Toms benchmarks for the Hd 7970 crossfire they used a Gigabyte z68 board with a 16x8x8 configuration. I was surprised at this so I'm thinking i can get away with the same, I just don't want to bottleneck the cards as you know running in a 16x8x8 will default both cards to running at 8x.

Also if your insisting on a 16x16x8 config can you recommend a well priced board.

Cheers


you can go with 16x8x8, only take 16x16x8 if the price is close.
m
0
l
February 2, 2012 2:08:24 PM

First off, I am assuming you have an Intel CPU? Personally, I would go with the x16,x16 mobo. If you are going to spend a lot on two graphic cards, you might as well get as much out of them as you can. If you give me a price range, I would be more than happy to help you find a mobo.
m
0
l
Related resources
February 2, 2012 3:47:00 PM

**WARNING** there are lots of issues with Crossfire, such as micro-stuttering. Tomshardware has a big article on this.

This card performs so well it's hard to recommend getting another one.

If you still think you might get one, may I recommend you at LEAST just get a single HD7970 and run it for a while to see how it goes?

Again, you will discover that most games will run BETTER with a single card than a dual setup because of these stuttering issues.

So you are sacrificing smooth gameplay in pretty much every game just to increase the frame rates in a small selection of games that can't actually run at the highest settings (and the gaming experience in these few games would still be better with the single card due to the micro-stutter).

What is micro-stutter?
Basically, Crossfire and SLI work by drawing the first FRAME on the first card, then the second frame on the 2nd card, then back to card #1.

However, because there is a small difference in what each card renders there is a small difference in time to draw.

If I was playing a game and panned from right to left the experience wouldn't be completely smooth. It's hard to describe, but obvious if you've seen it.

It would probably be very noticeable in games like Batman Arkham City.
m
0
l
February 2, 2012 4:00:13 PM

photonboy said:
**WARNING** there are lots of issues with Crossfire, such as micro-stuttering. Tomshardware has a big article on this.

This card performs so well it's hard to recommend getting another one.

If you still think you might get one, may I recommend you at LEAST just get a single HD7970 and run it for a while to see how it goes?

Again, you will discover that most games will run BETTER with a single card than a dual setup because of these stuttering issues.

So you are sacrificing smooth gameplay in pretty much every game just to increase the frame rates in a small selection of games that can't actually run at the highest settings (and the gaming experience in these few games would still be better with the single card due to the micro-stutter).

What is micro-stutter?
Basically, Crossfire and SLI work by drawing the first FRAME on the first card, then the second frame on the 2nd card, then back to card #1.

However, because there is a small difference in what each card renders there is a small difference in time to draw.

If I was playing a game and panned from right to left the experience wouldn't be completely smooth. It's hard to describe, but obvious if you've seen it.

It would probably be very noticeable in games like Batman Arkham City.



Thanks photon, I am aware of the issue you mentioned and have read the article. I am planning to start with one card and potentially move to a second at a later date, I just want to make sure my motherboard purchase is as future proof as it needs to be. For example if I will see better performance running my two radeon 7970s in the future in a 16x16x8 pcie configuration compared to a pcie 16x16x8 configuration. If i will see better performance in 16x16x8 then i will pay the extra for the motherboard however if they are going to perform the same due to the pci configuration not bottlenecking the cards there is not point spending the extra cash
m
0
l
February 2, 2012 4:11:47 PM

sandy bridge cpus have 16 pcie 2.0 lanes. they can support up to x8+x8 mode.
if you want x16+x16 mode, you'll have to get
  • a p67(b3) or z68 motherboard with nf2000 chip
    or
  • a sandy bridge-e cpu that natively support (no need for 3rd party chip) 40 pcie 3.0 and a motherboard with x79 chipset. something like this:
    http://www.newegg.ca/Product/Product.aspx?Item=N82E1681...
    some others:
    http://www.newegg.ca/Product/ProductList.aspx?Submit=Pr...
    btw, you'll find better advice in the motherboards section.
    m
    0
    l
    February 2, 2012 7:30:03 PM

    I have had a 5770/5750 and now I have two 6870's. I have not had issues with either. CF scales exceptionally well. At least for me it did.
    m
    0
    l
    February 2, 2012 8:37:39 PM

    yeah zero stuttering with the rig in my sig below (gtx 560ti SLi) absolutley amazing and smooth performance
    m
    0
    l
    February 2, 2012 9:11:32 PM

    Stuttering only seems to affect certain people, and is less obvious with more powerful cards (higher framerates)

    I have the asrock e4 gen 3 board. What you can consider is upgrading to Ivy Bridge when its out and only then crossfiring, as that will give you PCIe 3.0 16x, or 2x PCIe 2 16x i believe? Thats my upgrade route im planning on in future.
    m
    0
    l
    February 2, 2012 9:15:44 PM

    alwaysblur said:
    Stuttering only seems to affect certain people, and is less obvious with more powerful cards (higher framerates)

    I have the asrock e4 gen 3 board. What you can consider is upgrading to Ivy Bridge when its out and only then crossfiring, as that will give you PCIe 3.0 16x, or 2x PCIe 2 16x i believe? Thats my upgrade route im planning on in future.



    That boad is single @ x16 and dual @ x8. It is a nice board though.
    m
    0
    l
    February 2, 2012 9:24:41 PM

    That board is PCIe 3.0 capable, but itll only work with Ivy Bridge
    http://www.asrock.com/mb/overview.asp?Model=Z68%20Extre...

    I guess upgrading again to Ivy Bridge from SB isnt exactly cost effective, so you might be better off going for 16x, 16x now. I would wait though if I were you, shouldnt need that kind of power unless you're using eyefinity. plus the drivers arent quite matured yet, especially for crossfire, so crossfiring now will probably yield more problems.
    m
    0
    l
    February 2, 2012 9:50:15 PM

    OP: What kind of resolution will you be running? Up to 2560x1600 I would recommend at the most CF 7950s.

    If you are running Eyefinity 5760x1080 or higher, then you can probably justify CF 7970s.

    At 1080p, it would be a waste to buy two 7970s.
    m
    0
    l
    February 3, 2012 4:06:48 PM

    Wait till the 13th, pick up 3820 and X79. It'll be cheaper than Z68(NF200) + 2600K and you'll have out of the box pci-e 3.0 and support for x16/x16/x8. There is currently no 1155 board that can do x16/x16/x8 as it would require 40 pci-e lanes and as has been mentioned the maximum the chipset is capable of with a single NF200 bridge is 32 lanes x16/x8/x8.

    Seriously, the fact that you're even considering 3x gpus screams you need LGA2011.
    m
    0
    l
    !