2 x MSI 7990 , GPU 1 overheating

Hi,
My first mining rig/total newbie
Trying to setup 2 x MSI 7990, with one card i have steady 590-610khs per core with 75C temp each. When to cards are connected GPU 1 steadily overheats above 90C other 3 cores are fine with around 75C. Can’t get undervolting option unlock in Afterburner, other parameters are I’m tweaking as required. Is there any option in cgminer to get control over GPU 1 and get this temp down ?

RIPPEDDRAGON

If you go back a few months and look at reviews on the 7990 on its release you will find there are a lot of posts talking about the same problem. For some reason 2x7990s running together create a heat pocket on one GPU making it much hotter than the other 3. Unless you have them in an open air rig or have them water cooled I would not recommend running two on the same machine.

Thank you RIPPEDDRAGON for your quick reply. Only config which i found stable is moving the second card to PCIe x4 , but then system recognize only 3 GPU - that gives me between 1600 -1750khs with; I’m on Asus M5A99X EVO motherboard and obviously did not do my research correctly as I thought that system would see both GPUs on the card regardless of PCIex1/4/8/ 0r 16. Water cooling is out of question atm, but i do have access to the room which have 6 -12C ambient temp, (rig is open) so hopefully that would make a difference.
Once again thank you for your time RIPPEDDRAGON.

Managed to get temp under control but can’t get right the tuning of core 2/3.
Picture 002 shows the core 3 parameters which do not respond to any change, but it shows that is hashing ok, core 2 shows almost no hashing but all parameters are same like core 0 and 1 (and changeable) :
Mem 1500Mhz
GPU 850Mhz

Don’t know where the problem lies, anyone ?

My bat file :
timeout /t 10
setx GPU_MAX_ALLOC_PERCENT 100
setx GPU_USE_SYNC_OBJECTS 1
cgminer --scrypt -o stratum+tcp://coinotron.com:3334 -u xxxx -p xxxx -d 0,1,3,2 --intensity 13 -g 2 --thread-concurrency 8192 --gpu-vddc 1.087 --temp-target 76 --auto-fan --worksize 256 --scrypt
–failover-only -o stratum+tcp://pool2.d2.cc:3333 --scrypt -u xxxx -p xxxx

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mattmct

I have two 7950’s one was running much hotter than the other.

I realised that the card on the right was blowing its hot air directly on to the card on the left making it much hotter, as it was breathing in hot air, rather than cool air.

I had to down clock the card to the left. Until I got my risers, added some good space between the two, and added a 120mm fan to blow fresh cool air in between the cards (so the card on the left breathed in cool air).

Hey mattmct,
That was my problem too, one card on the riser sort the issue of overheating.
It maybe that I found solution for the conundrum with
Core 3, and those hashing rates all over the place :

possible that I need to get older drivers
most definitely need more RAM - it is recommended at least
same amount as on GPU’s and I have 12Gb vs 4Gb on motherboard…
Will shall see