Bitcoin Forum

 I recently build quad 7950 mining rig. all Saphire cards clocked to 1100/1500.
When I started cgminer I was getting 640kh/s, until temp risen to 70C, then it slowly dropped to 580kh/s per card.
So I removed 3 cards and let only one for further investigation.

I was not able to figure out why it has so low mining speed until I accidentally installed program called HWinfo64 (http://www.hwinfo.com/)
As I run the program I noticed that while memory clock were at 1500MHz, GPU clocks were changing from 1005 to 1050 every second.
After some trial and error I found that when I increase voltage on GPU (--gpu-engine 1100 --gpu-memclock 1500 --gpu-powertune 7) with cgminer powertune or in catalyst control panel to 7% or more GPU clocks were stable at 1100, not fluctuating anymore.

From now on my quad setup is running 640kh/s on each card total 2660 kh/s :)

maybe this can help some of you increasing hashing rates 8)
Of course temp was going up a bit, now I have around 76C per card, before it was 74C

Hi there, I also have Sapphire 7950 but got some issues with their LTC hashrate in cgminer (they were stable on similar frequencies). Could you please post the flags/settings you are using.

I am building a quad 7950 rig as well, do you mind sharing what driver / sdk versions and os you are using?

Try using the --intensity flag, value somewhere between 15 and 18 or so.

intensity 20 works for me but the system reacts very slowly, with intensity 18 the system reacts instantly.

Still cannot get the holy grail of 640 on my saphhires.  same clocks as op with power tune 10 only getting 600 and 580 out of the second card :/

are you undervolting at all? how much power you using?

Im at 600 hash with power draw of 640 ish :/

i see 640kh with 1075/1600/1.05v ... 1kw for a 4 card setup

wow ill try that out.  what other hardware is connected and what mobo btw?

Thanks!

Thats good, cos I have 7970 and I get around 660mb/h

all my 7950s run at 630

i have 83 7950 vaporx oc editons i run them at 1050 core 1250 mem 1.050 v i get 630-640kh  each card 700w from the wall 3 cards 920w from the wall 4 cards

Wow... both my 7950's are running at just under 600 kh/s and heating up to 80 degrees... I guess I still got some tinkering to do.

Where did you guys get the "plans" to build your rigs? I'm interested but dont know where to begin :(

One thing I've noticed that lowers temp is undervolting and decreasing power tune. If you get the clocks perfect you don't need as much power tune. Mine were all running 80 plus now their lower 70s down with more hash.

Just keep searching around! It's all on the forum just gotta do some digging and have some ingenuity...... And a very caring girlfriend/ wife lol

I find intensity of 13 to be the best.

depends if its a dedicated rig, 13 if you want to use your computer, dedicated 18 and above personally

Seasonic gold+ 1250w psu
ASRock 970 Extreme3 board
Powered riser cables
AMD Sempron 145
4GB ddr3 ram
Netgear usb wifi adapter
3 case fans and an old 80gb sata drive I had sitting around

hmm im not quite sure