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Crossfire 7970s x16/x4 Concerns - Possible test?

chivs688

chivs688

chivs688

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I've been looking over the past few days at adding a second card to my 7970, but realised when researching it a bit that my motherboard (Gigabyte Z77-D3H) only has a x4 speed PCI-e slot for the second GPU.

I've been trying to find out what degree of performance impact this would have, and have found a lot of varying reports on fps drop, and a few people saying it would increase the micro-stutter issue pretty badly (which is actually what concerns me the most, but can't test that out).

So I was thinking, regarding the performance loss, could I put my 7970 into the x4 slot now and see what kind of a performance hit that makes?

Then going off of that, wouldn't the Crossfire performance loss be a similar percentage of lost fps when compared with normal Crossfired 7970 performance? (Due to it essentially being two cards at x4 speed when Crossfired).
 
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About 5-10%, with 10% usually being a worst case scenario. Uncle Pete is your man for this. I believe he tried it recently on 7970 crossfire.
 
LtMatt said:
About 5-10%, with 10% usually being a worst case scenario. Uncle Pete is your man for this. I believe he tried it recently on 7970 crossfire.
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It was ages ago and fairly brief, but it worked fine from what I saw.

pandem0nium said:
Are they PCIe 2.0 or 3.0? x4 pcie 3 would be the same as pcie 2 x8, which wouldn't be much of a bottleneck at all.
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2500K, so 2.0.
 
I run a 2500k and xfire 7950s at x16/x4. In most games it is performing excellently. The only game I've had problems in is watch dogs which I'm sure is just the game. Wasn't far of benchmark scores of my bro running a 4770k with xfire 7970s at x8/x8
 
Heisenberg said:
I run a 2500k and xfire 7950s at x16/x4. In most games it is performing excellently. The only game I've had problems in is watch dogs which I'm sure is just the game. Wasn't far of benchmark scores of my bro running a 4770k with xfire 7970s at x8/x8
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Reckon I will beat you thoroughly pretty soon! ;)
 
Nope, even a Ti isn't a match for a couple of 79's bro! It does run them close in a few benchmarks, but overall the 79's have got a single Ti beaten by a wee bit.

2 Ti's on the other hand...
 
almighty15 said:
I ran 7950 crossfire at x16/x4 and it was horrible.
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in my experience this has been the case also.

However, i believe some slots are different, you can have a full 16x slot, but it might only be hardwired for 4x, some others could be a fully hardwired 8/16x slot but just running at 4x speed.

also as said, pci-e 2/3 can make a difference.
 
Thanks for all the replies.

Although some saying it works fine, others saying really bad hah.

My motherboard, Gigabyte Z77-D3H, has the x16 slot as PCIe 3, and the x4 slot as PCIe 2. So not sure if that means it's good, bad or in the middle in that regard.

I have considered maybe selling it and buying a better card, but would be a lot more hassle and likely for a bit smaller gain in performance..
 
The second hand price of 7970's right now you'd be silly to not at least try it! :D

I've run 2x7950's, 2x7970 and 1x7970 & 1x7950 all at 16x/8x and never noticed micro-stutter (but my eyes ain't as quick as they used to be and I've only played BF4/Titanfall with them) ;)
 
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