Topic: Mining With Multiple GPU Setup OC/Underclocking (Read 868 times)

Okay, so I'm a total newb but trying to get my bearings straight on this. I've been mining for about a month on my ATI 4870 card getting about 85 Mhash/s. I just recently purchased a Sapphire 7870XT with the intention of slamming out about 520 Mhash/s on it and creating with a dual card setup (for a total of around 600 Mhash/s). My intention was to have both GPUs mining, but the 4870 would be used less aggressively and used for my gaming and whatnot while the 7870 would be exclusively for mining. I've been reading around and it seems like people are having bits and pieces of my problem, but no solutions have worked as of yet.

Here are my problems:

-Unless one of the two cards are disabled, poclbm crashes on any miner used on client startup.
-When both cards are enabled, it appears to default to whatever gpu the active monitor i'm using is plugged into (I have two monitors, one plugged into the other card as a dummy). This is fine, however when opening Catalyst Control it only lets me configure that particular GPU (i.e. if my main monitor is plugged into the 4870, that's the only one i can configure and vice versa for the 7870). Once catalyst control center detected both cards but when I tried to switch between them to change the clock settings the system froze.

Here's where my issue starts to branch off:

-Under a single card setup, I can overclock the 4870 with no problems. When I overclock/underclock the 7870's gpu/memory clock (respectively), at the very least my mining (with any client) stops mining and the client freezes after 45 minutes to 1.5 hrs, and at most destabilizes and freezes my entire system (keyboard totally unresponsive, etc), which happens much more often when both cards are enabled.

I've installed the AMD APP SDK latest version for OpenCL, but am not sure if it needed to be installed twice (once for each card) but it doesn't seem to make a bit of difference. I have tried uninstalling/Driver Sweeper/Reinstalling for both GPUs, but to no avail. Anybody have any advice on how to get this going and stabilized? You would be my hero.



System Specs:
Hardware:
Intel Core 2 duo --CPU
ASUS P5Q-E LGA 755 --MOBO
ENERMAX 720W --PSU
Sapphire 7870XT --GPU1
ASUS ATI 4870 --GPU2

Software:
Windows 7 Professional x64
GUIMiner (primary)
BitMinter (rarely)