I have a somewhat similar problem, system suddenly hangs on p5q pro with 3hdd on raid0+5 and 2 hdd with sotware raid, 2 ext usb drives and esata hdd, chieftec new 750w is enough power for them , no event log on windows 7 x64 exect for sudden power failure. It happens either on sleep or while accessing drives from network. Didn't figured yet if it the intel chipset or jmicron esata to blame.
I have had a similar issue with my P5Q Pro. I have 2 x WD Rator's on the Intel RAID and 2 x 1TB Samsung F3's on the Marvell RAID, both in RAID1.
I used to have 2 x 250GB WD HDD's on the Marvell and never ever had an issue, not once. Since going to the Samsung's, I experience random freezes - usually when the disk is being is hammered If I press the reset button, when the POST is completing, I hear the F3's return to the park position.
Sometimes it does not totally lock up, I get 20 second bouts of freeze/unfreeze and I get this error in the event log:
The device, \Device\Scsi\mv61xx1, did not respond within the timeout period. - MV61xx
Followed by loads of NTFS erors. Both F3's check out 100% with the Samsung diag tool.
I'm running the latest FW/drivers, also I have my DVD-RW on the Marvell controller.
Running W7 x64