Crossfire 6950'slow FPS and GPU load

xfearshadowx

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Dec 4, 2012
2
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10,510
Hello, pretty simply put, I just recently went crossfire with two Twin Frozr iii Radeon HD 6950s. I have tried with many multiple games, and have had absolutely no luck with them. I either get the same FPS with much stuttering, or the FPS even lowers to an unbearable level. I can run everything much better with a single card, and watching with crossfire while I attempt to play skyrim, the FPS never goes past 35 FPS, and the GPU load never goes past about 40 percent. The CPU usage never jumps over 60 percent either so I'm completely out of ideas on what the problem could be.

Specs:
2x Radeon 6950 Twin Frozr iii PE/OC edition
700w power supply
MSI z77a - g41 motherboard
8GB RAM
Intel core i3 2100
 

cbrunnem

Distinguished
skyrim doesnt play well with crossfire in my experience as i do too have 2 6950s. i suspect a cpu bottleneck in some games though.

cpus arent used like you think they are. when a game is coded certain things are assigned to certain threads. for the most part what thread they are processed on doesnt change. for that reason there is always 1 core that is used more, the second a little less, the third even less. some games now a days are much better at this and can use 4+ cores but most cant. so it only takes 1 core to bottleneck your system and cause problems like you describe.

try overclocking a little in bios. you have limited overclocking ability with that board.
 

xfearshadowx

Honorable
Dec 4, 2012
2
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10,510
Alright, this was something I was really wishing wouldn't be a problem but it seems to be the only possibility. Luckily, I will be able to test the build with a friends i5 2500k this Friday, and hopefully I will recieve the desired results. If I do, I know what I'm asking for for Christmas, haha. And if I don't well I got a nice new motherboard and PSU out of this whole purchase.
 

lilgags

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Jul 17, 2012
33
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10,530
Im having this exact same problem...Im on an Asus Evo 990x with an FX-6100 OC'd to 4.2

My MoBo switches to 8x8x when crossfired, and I dont see any performance gain's (sometimes even worse) then when I run 1 card in 16x..
 

cbrunnem

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you both have weak cpus.
 

homiezheadsup

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Mar 14, 2010
64
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18,660
this is why i frequent Toms so often. Questions like this are often answered by Toms before I have to do any dirty work. The article basically tells you that Skyrim is very CPU dependent, and secondly that it doesn't work well in Crossfire. Pick another game and then compare the difference before thinking there is anything wrong with your system.

This is a quote from Toms: "Of the seven games tested, one doesn't seem to work with CrossFire at all. All seven support SLI.

Although the GeForce GTX 660 Ti loses to the Radeon HD 7950 most of the time in our single-card testing, a pair in SLI manages to outperform the 7950s in CrossFire three times out of seven (one of those clearly because CrossFire isn't working properly). Lets dig a little deeper, though. In Batman, CrossFire simply doesn't do anything for the AMD cards. In Battlefield, one GTX 660 Ti beats one HD 7950, so we'd expect two cards to demonstrate a similar outcome. Skyrim is really the only outlier, and we know that it's largely processor-dependent. Combine that knowledge with the experience of CrossFire having higher overhead and it makes more sense that the GeForce cards would shift into the lead."

http://www.tomshardware.com/reviews/geforce-gtx-660-ti-benchmark-review,3279-10.html