Crossfire, Motherboard and GPU Temp issues

[elison]

So I bought another Sapphire 6970 yesterday to crossfire in my rig, but a weird issue has come up.

Motherboard:
http://i47.tinypic.com/208wjmx.jpg


Link to my MB Manual: http://www.asus.com/Motherboards/Int...emeZ/#download

Reading through the MB manual, it states that the recommended lane usage to use dual VGA is PCIe x16/8_1 slot and PCIe x8_3 slot.

I had it configured like that when I first installed the card. However, after booting my computer up I immediately noticed that the cooling fan on the second 6970 (inserted into the PCIe x8_3 slot) I had purchased was on what I believe 100% fan speed. Weird. When Windows booted up, there was no CrossfireX option in CCC so I booted into BIOS and noticed that it wasn't even detecting the second 6970 I had installed.

I tried every slot possible on the motherboard and the only one that works in crossfire is PCIe x16/8_1 slot and PCIe x16_2 slot. The only thing is, especially with the size of these 6970s, that they are extremely close together, maybe 1/2 an inch apart. As long as it worked I didn't really care all that much.

Booted into Windows, everything was gravy. I then started watching my GPU temps. The top card idles anywhere from 46-53C, a good 5-10C more then the bottom card. I started Furmark and the highest the top card got to was 81C, while the bottom one was floating around 73C.

The temps are a little to high for my liking and I would like to know why I can't use the manufacturers recommended PCIe lane usage. Obviously if they did, I believe that the airflow would be a bit better and could possibly drop my temps a little. Maybe I'm just being anal.

Any ideas?

[Artemicon]

Your slot issue intrigues me more than the temps, it seems that might be a software or recognition issue.

Temps though I thought in a normal upright configuration that the top card is always a few degrees hotter due to the rising heat but I don't really have experience with sli/xfire so I guess until someone more experienced comes along take that with a grain of salt.

[Eggroll]

Yeah up to about 10c more on the top card is normal. Are you manually adjusting fan speeds also? I'm using a set of 6870s and they'll hover around 80-85 on automatic settings and the fan speeds pretty much never break 30%, manually setting it 40-50% practically guarantees sub-75 degree temperatures/

[elison]

Yeah up to about 10c more on the top card is normal. Are you manually adjusting fan speeds also? I'm using a set of 6870s and they'll hover around 80-85 on automatic settings and the fan speeds pretty much never break 30%, manually setting it 40-50% practically guarantees sub-75 degree temperatures/

Yeah, I'm using MSI Afterburner with custom fan speeds.

Also, I figured out the issue. Apparently my mobo has switches that turn on/off PCIe bridges (was this shit necessary?) that I never saw. Just so happens that 3/4 were switched off for whatever reason. Got it setup on 1/3 bridges and my GPUs haven't broken 75C yet.

Thanks for the tips you two.