I'm running 2 GPUs on 700w PSU. One 7970 and second 7950. I get 1300Khash with GUIMiner scrypt (Litecoin).
There could be cooling issue as I had. After about 5 minutes upper GPU swhiched off...
I installed additional vent to blow between GPUs and turned voltages down. GPU temp dropped 18-20c
Topic: 2x ASUS 7950 low voltage problem - page 2. (Read 2886 times)
@toolbag and @gurvy: Thank you very much for the answers .. is there maybe a way to determine by other means if the PSU is overrated? I guess I need to get a 1200W gold and then retest. Will report my findings.
second vote for the power supply. they can draw alot
Are you sure it's not just a faulty/undersized power supply? Many power supplies can't put out anywhere near their rated wattage. I just got into mining myself with a single 7870 and I bought a 630W power supply just to be sure I had enough overhead to handle the card.
Hi everybody,
I'm relatively new to mining and have the following setup:
Graphic cards: 2x ASUS HD7950 DirectCU II TOP GDDR5 3GB 384Bit AMD Radeon DX11.1;
MB: ASUS M5A99FX PRO R2.0 AMD 990FX/SB950 DDR3 2133MHZ(O.C.);
CPU: AMD FX X4 4100 SOKET AM3+ 3.6GHZ 12MB CACHE 32NM;
RAM: CORSAIR 8GB VENGEANCE DDR3 1600MHZ CL10 (single module);
PSU: GX 80PLUS 750W (bronze, 85% efficiency);
I don't use any risers; if a test each device separately I get a performace of about 580kH/s @ 1.090V (did not tweak extremely long, might get higher numbers); this is fine. But when I try both cards together then one of then cards voltage drops to 0.800V with corresponding engine clock down to 300Mhz; the other cards is fine but my overall performance is lower than 580kH/s.
I tried increasing the SB (Southbridge) voltage in the BIOS but that did not help at. Tried to combine a Sapphire 7950 with an Asus 7950 and got the same problem: One of the cards has systematically significant lower voltage (and therefore lower engine clock). I'm quite stuck .. I suspect the motherboard, but I feel with all its tweakable parameters a litte overwhelmed ..
I'm relatively new to mining and have the following setup:
Graphic cards: 2x ASUS HD7950 DirectCU II TOP GDDR5 3GB 384Bit AMD Radeon DX11.1;
MB: ASUS M5A99FX PRO R2.0 AMD 990FX/SB950 DDR3 2133MHZ(O.C.);
CPU: AMD FX X4 4100 SOKET AM3+ 3.6GHZ 12MB CACHE 32NM;
RAM: CORSAIR 8GB VENGEANCE DDR3 1600MHZ CL10 (single module);
PSU: GX 80PLUS 750W (bronze, 85% efficiency);
I don't use any risers; if a test each device separately I get a performace of about 580kH/s @ 1.090V (did not tweak extremely long, might get higher numbers); this is fine. But when I try both cards together then one of then cards voltage drops to 0.800V with corresponding engine clock down to 300Mhz; the other cards is fine but my overall performance is lower than 580kH/s.
I tried increasing the SB (Southbridge) voltage in the BIOS but that did not help at. Tried to combine a Sapphire 7950 with an Asus 7950 and got the same problem: One of the cards has systematically significant lower voltage (and therefore lower engine clock). I'm quite stuck .. I suspect the motherboard, but I feel with all its tweakable parameters a litte overwhelmed ..
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