Bitcoin Forum

Hello good folks, I am currently having problem achieving the expected hash rates with my cards.

Specs:
3x XFX Radeon HD 7950 3GB GDDR5
MSI Z77A-G45, Socket-1155
Corsair Vengeance DDR3 1600MHz 8GB CL10
Corsair CX 750M, 750W PSU
Intel® Xeon® Processor E3-1240V2

Configuration with hash rates below:
https://i.imgur.com/uOhN4uO.png
https://i.imgur.com/JEUanVL.png

It is to be noted that the card i think i am having problems with are using converters from molex -> 6pin and 8pin to the GPU


Any tips or ideas that i can try out?

What hash rate were you expecting? LTC mining has a lot lower hash rate than BTC mining. Those hash rates look about right I believe.

Or if you're asking about why your GPU1 is occasionally dropping out to ~60% usage, it may be because of how hot you are running your cards (101 C?).

Hehe yes, i know that the card is probably a bit to hot.

But the problem is the card that is getting 354khash/s, and yes i know the hash rate is lower on LTC.

But the card shud be able to perform about 450khash/s, but i cant get it to do that.

maybe it's a pcie bandwidth issue.  some expansion slots can fit a x16 card but are really only x8 on the board.

although I doubt bus width is important for mining now that I think about it...

2 of the cards are placed in PCIe 3.0 x16 and the last one is placed in a PCIe 2.0 x16 slot. Could this be a problem?

From what i have read it shudnt be a problem.

You have it underclocked, undervolted, etc, compared to the others. Not sure why you wouldn't expect it's hash to be lower. Have you tried turning off the other two, letting the middle one cool down, put it to the same settings as the others and see what performance it gets? You can also try just swapping its slot with another one.

I have not changed the voltage, the card is downclocked a bit so it wont overheat. The card i am having problems with is labeled GPU3 the one wich is clocked highest and has the best cooling.

I might try to change up the placement of the cards later on.

My immediate guess would either be temperature or running all three on 750W. But since you said its GPU3 which seems to have the lowest temps, so not to sure. Maybe you should try undervolting that card, heard alot of people doing that with similar set ups. I definitely understand what your saying about it not having the expected hash rate, most people I read on the forum are expecting 500-550 on those cards.

Yeah the rates are definitely low - that card is good for 500+ easily.

Unfortunately no idea what the problem is - I am facing a similar issue (identical hardware that performs wildly differently even given the exact same settings/configs/etc).

Ok, thx for the feedback. Think i will take a look at it after work today. Maybe i will post pics :)

Bandwidth is not a problem.

My guess would be CPU or memory over usage. Unless there is something very obvious being overlooked.

Omg, 100 degrees :o Buy cooler, man ;)

Dude those temps are crazy hot, your cards won't last long at this rate