cgminer freezes at random intervals I have just recently built a mining rig. The problem I am running into is that cgminer will randomly "freeze" while mining. When I say freeze cgminer will just stop accepting shares and the GPU data will stop updating; however, I am still able to issue the 'Q' command, but it does not work. I have tried everything I could think of to attempt to fix this problem. Re installing Xubuntu, lowering memclock, lowering engineclock, lowering intensity, lowering thread-concurrency, increasing voltage, upgrading/downgrading cgminer, etc. The odd thing is the fact that none of the cards crash or go sick before cgminer freezes, and you see no increase of GPU temps when cgminer does crash. The period of mining before crash seems to be completely random. It has crashed 30 seconds after startup and it has crashed 4 hours in (which was the longest uptime and it was on a higher memclock and engine clock than I am on now). To me this makes no sense why it would be crashing at all, for the cards seem perfectly stable with the settings.

System Specs:
CPU: FX 4130 quad core @ 3.8GHz, 8 MB Total Cache
PSU: HALE90 V2 1200W
GFX: 4x PowerColor HD7970 3GB GDDR5
RAM: Ballistix (by crucial) 4gb DDR3 1600MHz
SSD: SanDisk 64GB 6Gb/s
MOBO: 970 Extreme4 Socket AM3+ ATX AMD motherboard
OS: Xubuntu 12.10 x86_64

cgminer Start Parameters (start.sh script):
export DISPLAY=:0
export GPU_MAX_ALLOC_PERCENT=100
export GPU_USE_SYNC_OBJECTS=1
./cgminer --scrypt -o http://poolurl.com:8080 -u username -p password -I 13 -g 2 -w 256 --auto-fan --temp-target 70 --temp-overheat 85 --gpu-fan 75-90 --thread-concurrency 8192 --gpu-engine 1106 --gpu-memclock 1825 --lookup-gap 2 --gpu-powertune 20

cgminer version is 3.7.2.

If you need any more information just ask. Any help will be appreciated, for I am absolutely stumped on what is causing the problem.

Thank you,
    Kyle
I d recommend to try bfgminer , a more secure and robust fork of cgminer : 

http://bfgminer.org/

https://github.com/luke-jr/bfgminer