Topic: Consolidated Litecoin Mining Guide for 5xxx, 6xxx, and 7xxx GPUs - page 11. (Read 624200 times)

Can anyone comment on using PCI-E risers?

I just implemented a third card on a rig using a riser - and the card in the third slot that is on the riser is only getting like 350k/H - where the other 7950 in directly in slots 1/2 are getting 550k/H.

Can riser lower hashrate that much?  Also the card with the riser won't let me set fan speed in cgminer?

I have no app-sdk installed at all and everything works fine.

The 2.7 SDK gave me a lot of troubles with compiling new .bins. Try uninstalling it and installing 2.5 or 2.6 instead and delete all .bin files in your miner's folder and try again

I'm running HD 7950 and 7770.
Here's the command line for cgminer that I pass it:
cgminer.exe --scrypt -o stratum+tcp://site -u username -p pass --shaders 1792,640 -w 256,256 -v 1 --intensity 18,14 -g 1 --thread-concurrency 21712,8000 --lookup-gap 2,2
and I get an error for the hd7950 device:
Error -5: Enqueueing kernel onto command queue. (clEnqueueNDRangeKernel)
Is there any way to fix this? It seems that no program accepts high values for thread concurency for me although I already set a global value for GPU_MAX_ALLOC_PERCENT 100
I also seem to get a lot of HW errors for 7950. I have catalyst 13.3 and app-sdk 2.7 installed.

unless you undervolt your gpus, 850w isn't gonna be enough. that boost card pulls ~300w each with default voltage setting.

I thought about this stuff also..gonna try some changes ..strage thing is that the last setting i used with afterburner worked and the sistem was getting 1500 ..but the pool was registering only 500 than i stop stated it again and crashed. Also i started all the miners with a gab better util each one got stable

Couple of ideas:
1. not enough power to the system, once you start the 3rd card the system will crash out, I would have thought 850w should be enough though.

2. getting too hot - run with case open and a big fan pointing straight at system.

3. one card is faulty - try mining with each card for an hour by itself.

For 1 and 2 undervolting may help. You should be able to drop the volts (VDDC in afterburner) to 1.030 at stock clocks.

Good call on the undervolting, if I undervolt my 7970's to 1.025 they will got "sick" once or twice a day. At 1.030volts they are constantly fine.

sorry for very late reply,

power limit setting on msi afterburner, i have 2x His 7950 iceq having same problem, after i set my power limit to 10-20%, they all ok now.

Hello all,

Unfortunately i am facing some real problems with my new rig, this is the setup i just received:

CPU: AMD - Procesor AMD Athlon II X2 Dual Core 250 (C3) (BOX)
MotherBoard: GIGABYTE 990FXA-UD5, AMD 990FX + SB950, AM3+, DDR III, USB 3.0, PCI-E 16x, SATA III
PSU: Antec HCP-850, 850W, Modulara, Vent. 135mm, Efficiency 92% (80 PLUS GOLD)
Ram: Corsair Vengeance DDR3, 2x4GB, 1600Mhz (Dual Channel)
Case: CoolerMaster - CoolerMaster HAF 932 Advanced
Hdd: some old suff i found at home
Video Card:3 x Sapphire Radeon HD 7950 Boost, 3GB, GDDR5, 384bit, DVI, HDMI, Mini-DisplayPort, PCI-E 3.0

On a fresh windows i have installed the following:

MSI Afterburner
AMD SDK
AMD Drivers 12.8
GUIMiner

Start 1 #1: I run the miner on the first to GPU, good hashrates ±560, when i start mining the 3rd GPU-system crash/shut down

I thought i had to undervolt or something and restarted the computer.
I run cmd and enter: startx GPU_MAX_ALLOC_PERCENTAGE 100

and enter various settings in afterburner that i found on the forum, for one setting the rig lasted a little bit with all the GPUs started (although the pool did not show the same hashrate) but when i closed one GPU and started it again same thing happened.

Also with different afterburner settings even with 2 GPU running it crashed

I also watch the GPU temperatures, it reached 90c on some settings - on other settings the GPU temperature was quite ok (maxing 81 for one GPU the others at about 60) but the GPU was reaching 99% constantly (on other settings the was to change in load).

Any ideea how to fix ? do you have some recommended settings ?

I haven't done anything with them.....

did you undervolt it?

I always run my 7950s at 20.  I'm guessing if you go to high with your settings or intensity either can make it go awry. 

I'm using these stock clocks which are 925/1250.... Lowered intensity from 20 to 18 and no issues so far.

I had that issue yesterday while I was trying some different configs for my 7950s.  After I lowered the gpu clock and memory clock back down to somewhat reasonable levels (1100/1600) all has been well since.

Is there a reason why every so often one of my 7950's says "SICK" or "DEAD"? The temps don't go above 80 C.

In the start menu, right click on Computer, click Properties, click "Advanced system settings" on the left, click "Environment Variables" in the Advanced tab, find GPU_MAX_ALLOC_PERCENT and click delete. Reboot.

how to undo option setx GPU_MAX_ALLOC_PERCENT 100 ?

Hi there. I followed the advice from the topic's "first post" and typed in "setx GPU_MAX_ALLOC_PERCENT 100" on my Windows 7 x64 machine, hoping that I would see higher speeds in cgminer, but now my hashrate has dropped. Instead of the usual 740-770K I was getting from my 7970s they're now hashing at 560-640K which is not cool at all. What exactly does that setting do and how do I undo it? Re-installed drivers already with AMD cleanup utility and Driver Fusion after that, but still not getting the usual hashrate..
UP: found a solution, after typing in "setx GPU_MAX_ALLOC_PERCENT 100" it's now mandatory to specify in cgminer's .bat-file "thread-concurrency 8192", otherwise the hashrate is lower. Apparently this playing with max_alloc only causes harm in some cases.

already ordered the 7970=P
Still have 2x pci-e16 slots over, so might go for those in the future.
Btw, are ALL of those cards voltage locked? Or just the newer editions? And what temperature are your cards at when mining?
Even if i manage to burn it out after a while, 2 year waranty should help, no?