2 identical rigs, 1 have HW error other don't.

Hey,

So I set up two motherboards with 3x Toxic each. Lets call them rig1 and rig2.
Everything is identical so no idea why they don't act/work the same and I'm using CGminer 3.7.2. This version worked the best, meaning it reduced my HW errors a little bit.

Currently using ATI Display Driver ver. 13.2. I tried the beta but with the same results.

This is what I'm using in my .bat-file.

Code:

setx GPU_USE_SYNC_OBJECTS 1
setx GPU_MAX_ALLOC_PERCENT 100
--scrypt -g 2 --thread-concurrency 15236 --intensity 13 --gpu-memclock 1800 --gpu-engine 1500

I'm using this tc because lower and the rig immediatly froze. Likewise if I removed it and used shader 2048 instead, immediate crash.

( CGminer shows gpu0, gpu1, gpu2, same on both rigs )

Rig1 runs perfectly fine, no HW error / freezes, at 800kh each gpu.

Rig2 on the other hand gets approximately 8 HW error per hour on gpu1. I tried fixing this by downclock gpu1 but when I did gpu2 crashed immedtialy and I don't know why.
I even tried using stock and/or lower clocks but it ran for approximately 5-10min before the whole rig crashed.

I also tried -g 1. It lowered the hashrate but kept the HW errors.

So any idea what might cause this? Huh

Any help would be appreciated.

P.S. I'm very new to mining which is why I have no idea what might cause this and I can't find any answers searching the web which is my I'm turning to you.

Regards
Freyja