Are you watching it to see that it shuts down immediately when entering sleep, or is it possible it enters actual sleep mode (pulsing light on the front) and then shuts down sometime later?
Reason I ask is that Windows settings (I believe) are to sleep for a while and then hibernate--which is where the contents of RAM get written to a file on the disk and then the computer does completely shut down. Turning it back on should initiate a process that reads the hibernation file from disk back to RAM and returns you to exactly where you were, but sometimes that doesn't work properly.
Macs have hibernation functionality too but I've only ever seen it used in battery powered Macs when the battery level gets to a critical level.
Edit: Do you have a MacOS drive/partition also? Does sleep work properly there? If so then your PSU is not the problem.
Well I mean as a matter of testing you should reboot into MacOS and manually put it to sleep via the Apple menu. If it enters sleep mode (pulsing white light) and you can wake it up normally then there's nothing wrong with your power supply.
If you've only just now disabled hibernation I would give it some time and see if that resolves the issue on the windows side. Keep us posted.
Do you have the intel chipset drivers installed? Not sure if Intel provides a download for the X58 or if Windows Update automatically takes care of it.
I would disable sleep altogether in Windows and then leave the system for a day or two and see if it stays online. If so, then you know the problem has something to do with sleep.
A longshot--you don't have the Mac Pro on a UPS battery backup with the USB cable connected, do you? I just remembered I had a similar issue a couple of years ago (although this was in OS X) and it was my UPS sending erroneous signals to the Mac to shut down.
I would pull all other drives than the boot drive, pull all PCIe cards other than the video card, and pull all RAM sticks but 1. Re-enable sleep in Windows and see if your shutdown issue goes away. If it does, then add stuff back one at a time in order to isolate what hardware is causing it.
If it still shuts down with the stripped down config then you might try a new windows install onto another disk or partition just to rule out some sort of bad driver/configuration issue on your existing bootcamp partition.
Do you have the intel chipset drivers installed? Not sure if Intel provides a download for the X58 or if Windows Update automatically takes care of it.
I would disable sleep altogether in Windows and then leave the system for a day or two and see if it stays online. If so, then you know the problem has something to do with sleep.
A longshot--you don't have the Mac Pro on a UPS battery backup with the USB cable connected, do you? I just remembered I had a similar issue a couple of years ago (although this was in OS X) and it was my UPS sending erroneous signals to the Mac to shut down.
I would pull all other drives than the boot drive, pull all PCIe cards other than the video card, and pull all RAM sticks but 1. Re-enable sleep in Windows and see if your shutdown issue goes away. If it does, then add stuff back one at a time in order to isolate what hardware is causing it.
If it still shuts down with the stripped down config then you might try a new windows install onto another disk or partition just to rule out some sort of bad driver/configuration issue on your existing bootcamp partition.