Triple Crossfire CPU Bottleneck

[Danice123]

Specs:
ASRock 990FX Extreme9 motherboard
8GB Ram
AMD FX-4350
Antec HCG-850M
3x Radeon HD 4850s (512MB ram)

When I built my rig, I was trying for cheap, so I picked up three 4850s for cheap and figured crossfire-ing them should give me some power. And they run really well, but I think I'm running into some problem with a bottleneck with the CPU. A couple games I've run into have been running my cards at about 50% - 70% and then maxing out my CPU cores, which seems strange to me, since 4850s are pretty old, and this processor is new and pretty (for an AMD) powerful. Battlefield 3 was as expected, since its pretty CPU heavy, but I've been playing Arkham Asylum and I'm getting <20 fps and maxing out my CPU, which seems strange to me, as according to Google just ONE of these cards should have been able to run the game with a processor from 4 years ago with better results than I am getting. Is the crossfire itself getting in the way? Do I need to upgrade my CPU to one with more cores?

 

[Lee Yong Quan]

i think problem lies in the card. three way sli is too much. just take a gtx 760 or hd 7870 should do better than it.

 

[Danice123]

i think problem lies in the card. three way sli is too much. just take a gtx 760 or hd 7870 should do better than it.

Too much as in...? And its crossfire. And the point is not to spend money. And it works great on benchmarks (3DMark). So why doesn't that transfer?

 

[Apbg10]

Batman games typically run better on nVidia cards, so that may explain part of the low fps, but I'd say upgrade your GPU to as Lee Yong Quan said, something like a 760 or 7870. Both are cheap and run well.

 

[Danice123]

Batman games typically run better on nVidia cards, so that may explain part of the low fps, but I'd say upgrade your GPU to as Lee Yong Quan said, something like a 760 or 7870. Both are cheap and run well.

That may be it. The whole old card/not nVidia/crossfire may be screwing with the game.

 

[maxalge]

i think problem lies in the card. three way sli is too much. just take a gtx 760 or hd 7870 should do better than it.

Too much as in...? And its crossfire. And the point is not to spend money. And it works great on benchmarks (3DMark). So why doesn't that transfer?

Too much as in lower level amd cpu's like the one you have are known to bottleneck multi gpu setups.


Cpu cant keep up.


You can test this by overclocking your cpu.

 

[Lee Yong Quan]

i think problem lies in the card. three way sli is too much. just take a gtx 760 or hd 7870 should do better than it.

Too much as in...? And its crossfire. And the point is not to spend money. And it works great on benchmarks (3DMark). So why doesn't that transfer?

excellent 3dmark score does not really reflects on gaming experience. card like that hd 4850 (older)although is three way sli but still wont perform anywhere near a hd 7870 in gaming (smoother, less stutter, better fps) so i believe it is the card setup problem. if you get a hd 7870 or gtx 760 battlefield 3 could reach somewhere high to very high setting depend on your resolution of course

 

[Danice123]

i think problem lies in the card. three way sli is too much. just take a gtx 760 or hd 7870 should do better than it.

Too much as in...? And its crossfire. And the point is not to spend money. And it works great on benchmarks (3DMark). So why doesn't that transfer?

Too much as in lower level amd cpu's like the one you have are known to bottleneck multi gpu setups.


Cpu cant keep up.


You can test this by overclocking your cpu.

Ok, so it could be a CPU bottleneck and not a hardware compatibility problem. I'm guessing that a better CPU means getting more cores, not raw speed? Or are you saying AMD in general?

 

[maxalge]

i think problem lies in the card. three way sli is too much. just take a gtx 760 or hd 7870 should do better than it.

Too much as in...? And its crossfire. And the point is not to spend money. And it works great on benchmarks (3DMark). So why doesn't that transfer?

Too much as in lower level amd cpu's like the one you have are known to bottleneck multi gpu setups.


Cpu cant keep up.


You can test this by overclocking your cpu.

Ok, so it could be a CPU bottleneck and not a hardware compatibility problem. I'm guessing that a better CPU means getting more cores, not raw speed? Or are you saying AMD in general?

Some games are cpu bound, and sometimes need overclocked cpu power to run smoothly.

Try disabling the other 2 4850's and running only a single one and post back if there is any difference in fps in arkham.

You have installed the newest drivers/ CAP profiles?

 

[iam2thecrowe]

also they are 1gb cards, and 1gb vram is not enough to run current games smoothly. sell them and get a better single card.

 

[Danice123]

i think problem lies in the card. three way sli is too much. just take a gtx 760 or hd 7870 should do better than it.

Too much as in...? And its crossfire. And the point is not to spend money. And it works great on benchmarks (3DMark). So why doesn't that transfer?

Too much as in lower level amd cpu's like the one you have are known to bottleneck multi gpu setups.


Cpu cant keep up.


You can test this by overclocking your cpu.

Ok, so it could be a CPU bottleneck and not a hardware compatibility problem. I'm guessing that a better CPU means getting more cores, not raw speed? Or are you saying AMD in general?

Some games are cpu bound, and sometimes need overclocked cpu power to run smoothly.

Try disabling the other 2 4850's and running only a single one and post back if there is any difference in fps in arkham.

You have installed the newest drivers/ CAP profiles?

I do indeed. I will check this.

also they are 1gb cards, and 1gb vram is not enough to run current games smoothly. sell them and get a better single card.

Which is what I would have thought, except that I do run most current games smoothly. I average 30-40 fps running games using double to triple the vram that I have. Mass Effect 3 is very playable at 1080p, BF3 is at a slightly lower resolution, mostly because I need higher fps there. And Arkham Asylum is definitely CPU bottle necked, my cards are all running at 40%-50% while playing.

 

[Danice123]

After testing the game with different cards, it seems that is is not a CPU problem, the CPU seems to be running at the same usage no matter how many cards I use.

1 card was maxed at 99% GPU usage, 2 cards had about 60% usage, 3 cards around 40%.

So the game seems to be bottle necked by something else. I tested different resolutions and got FPS gains on lower, obviously, so I wonder if the vram could be bottle necking? The read-out on my vram monitor says that im useing 1GB to 1.3 GB of vram, I' guessing that would the memory of all three. I would figure that it would read 1.5GB if it was maxed?