6850 Crossfire not performing as expected

[beewomp]

Here's my specs:

ASUS P8P67 LE Motherboard
Intel Core i7 2600 @ 3.4ghz
8GB DDR3-1333
Corsair CX600M PSU
2x Gigabyte ATI Radeon HD 6850 (GV-R685OC-1GD)

I actually notice a significant performance decrease after enabling Crossfire. I've tried uninstalling/reinstalling drivers, using CAP profiles, swapping the cards in their slots, taking out my PCI sound card... all things I've read in similar threads, to no avail.

In Battlefield 3, there is simply a framerate decrease. In Bioshock Infinite, there is a terrible stuttering (far worse than micro-stuttering; I know the difference) that sometimes actually freezes entirely for a second or two.

Both cards, on their own, run these games on High to Ultra decently. But with Crossfire enabled, it turns to crap.

I am lost, and have two perfectly working, identical cards* that just do not want to play together. What should I do?

*The only difference in the cards I've noticed, is one seems to have higher maximum GPU and memory clock settings for overclocking. But, from what I've read, they should just simply use the clock speeds from the slower card. AKA not perform worse than either card would alone.

 

[oddlyinsane]

Seems like micro-stuttering. Try using RadeonPro.

 

[beewomp]

Seems like micro-stuttering. Try using RadeonPro.

Well, I would understand micro-stuttering if the games were running smoothly in between hiccups. However, they are not; the overall framerate drops as well.

 

[oddlyinsane]

Check if any of the GPUs are underclocking. Use Afterburner to check temps and GPU activity.

 

[iam2thecrowe]

crossfire is poop. end of story. I used to run crossfire 6850's a few months ago, sold them both and got a single gtx660. now games run smooth. Some games indeed ran better with a single 6850 than with two of them. Do you have a crossfire bridge installed, you should see some increase in framerate with fraps, even if it doesnt translate into a real perceptable fps increase on your screen. Also if you run crossfire with one card in a 4x slot you will also get poor performance, and your motherboard has a 4x and 16x slot, so thats probably your issue. sell those cards while theyre still worth something and get a good single card solution.

 

[beewomp]

Check if any of the GPUs are underclocking. Use Afterburner to check temps and GPU activity.

Just ran a BF3 Ultra test. Both cards showed 875/1200mhZ for GPU/clock. Temperatures were pretty normal, at about 55 degrees each. It was showing ~80-95% GPU activity for both cards, and my FPS hovered around 20-35 in battle with bad stuttering mixed in. Just awful.

 

[beewomp]

crossfire is poop. end of story. I used to run crossfire 6850's a few months ago, sold them both and got a single gtx660. now games run smooth. Some games indeed ran better with a single 6850 than with two of them. Do you have a crossfire bridge installed, you should see some increase in framerate with fraps, even if it doesnt translate into a real perceptable fps increase on your screen. Also if you run crossfire with one card in a 4x slot you will also get poor performance, and your motherboard has a 4x and 16x slot, so thats probably your issue. sell those cards while theyre still worth something and get a good single card solution.

Hahah so why do they even advertise it's a "Crossfire Ready" board? In case I just want the inside of my case to look more full? I'm so fed up with the issues, I may just take your advice, if it really is hopeless with my setup.

 

[iam2thecrowe]

crossfire is poop. end of story. I used to run crossfire 6850's a few months ago, sold them both and got a single gtx660. now games run smooth. Some games indeed ran better with a single 6850 than with two of them. Do you have a crossfire bridge installed, you should see some increase in framerate with fraps, even if it doesnt translate into a real perceptable fps increase on your screen. Also if you run crossfire with one card in a 4x slot you will also get poor performance, and your motherboard has a 4x and 16x slot, so thats probably your issue. sell those cards while theyre still worth something and get a good single card solution.

Hahah so why do they even advertise it's a "Crossfire Ready" board? In case I just want the inside of my case to look more full? I'm so fed up with the issues, I may just take your advice, if it really is hopeless with my setup.

even with my setup, 8x/8x slot at pcie3 speeds (essentially pcie2 16x), i still suffered poor performance and stuttering in some games. A few games ran ok, crysis 2 ran ok, skyrim ran ok without the high res texture pack otherwise it would stutter in outdoor areas due mostly to lack of vram, dead island was full of microstutter, bf3 ran like poop ran better on 1 card. Thats another thing 6850's in crossfire miss out on, 2 x 1gb cards in crossfire still only gives you 1gb useable vram. most games now have high enough res textures to use much more than 1gb vram, and when you do that with a 1gb card it spills to slow system memory giving big slowdowns and stuttering.