Solved\ Random lockups/system freezes AMD 6850 crossfire mode

Question

Hello all,
I have come to these forums because i have a problem for 4 months now and i cant seem to figure out.
First my systemspecs:
Asrock X79 extreme 4 slot 2011 (Bios version 2.0 (latest))
Intel i7 3820
16 Gig Geil 1600 DDR 3 memory (4 dimms)
2 x MSI R6850 Cyclone Power Edition/OC (crossfire mode with bridge)
1 x OCZ agility 3 SATA III 2.5" SSD 120GB (System drive)
2 x Samsung HDD 500GB 7200rpm
TG600-BZ 600 Watt maxx 24 amps
Running Windows 7 64bit
Catalyst 12.6
12.7 CAP1
So my problem:
When i have 2 cards inserted in crossfire mode my system goes true random lock ups and freezes. Up to several times a day.
While heavy load and gaming i sometime hear the system hang for a few seconds (sounds hangs system freezez) and then it continues to run.. usually that happens about 5-6 times before the system hangs locks up and does not respond anymore.. (i can hear the sounds hanging) and have to do a reset.
I had a few BSOD's getting the well know ATIKMPAG.sys error but that happen only twice.
Funny thing is that it does not always does this while under heavy load but also while doing YouTube video's.. even had one while cooking dinner.. (computer not in use).
Seems to be completely random.
So what have i done to fix the problem:
I have done a complete clean install of windows 7 only running basic drivers and hardware.. problem persists
Check system event log on any problems but since it does sudden lockups there are no logs of these hardware events.
Did a check on my power saving options in windows.. made sure all were on performance.
I have run true Catalyst 12.1 to 12.6 and all kinds of cap's.. problem persists
Checked temp, does not come above 70 degrees Celsius.  (case temp not above 30)
Made sure i run the latest BIOS version of my motherboard.
Run a 24 hours memory test with memtest86+ no errors.
Did a heavy load and MSI burn in test on the single cards separately from each other continues to run perfectly.
I have run both cards separately from each other in my system (single card mode) for 2 weeks...(both PCIE slots) system runs like a charm.. no lockups no random freezes.
So i hope anyone can help me, i have some experience troubleshooting computer problems but this one has me baffled.
TheAbeL

Answer 1

Quote from: TheAbel on 19-July-12, 14:19:47
This is indeed the Tagan piperock 600 watt. Problem is that i have no idea how much amp my cards are pulling from 1 rail.. are they trying to pull it all from 1 rail? or are they getting power from 2 different rails. If my crossfire setup is pulling al his power from 1 rail i still have a problem..
Also i read in the review (my german is rusty but ok, tnx xmad) that when turbo mode is enabled that all rails work as one rail.. so 80 amp is available? Is this even possibly?
My new PSU will arrive today so i will report tomorrow if it has solved the issue or not.
 No, as noted in my last reply for your PSU: "48A combined total for +12V rails". Max for any individual 12V rail is 20A. If three of the rails are loaded to total of 48A then the 4th is useless. You can't just add up 20+20+20+20 & come up with 80, it doesn't work that way on PSU although Antec seems to think so.