P5E w/ Vista 64, two SATA hard drives in AHCI mode, built in January. Ongoing problem with spontaneous reboots, about once per week. Found that it coincided with the weekly defrag schedule, and that I could force the BSOD by running a defrag manually... but only with both drives selected for the defrag. If I selected only one or the other, it would run. Disabled the scheduled defrag, but still experiencing random reboots... anywhere from 1-2 weeks in between each.

I can run P95 or Memtest for days without errors. I can play UT3 for hours without a problem. So, my conclusion was bad mobo drive controller, bad hard drive, or Intel matrix storage driver is flaky under Vista64.

Then one day I came home and the computer had rebooted, and was sitting there in the pre-OS environment complaining about no OS found. Went into BIOS and found that it had made my storage drive the primary drive. Switched it back and rebooted. When it got to detecting AHCI port on the OS drive, it froze. Rebooted, and it worked OK this time. I've since noted that occassionally during the AHCI port detection phase it will go very slowly, whereas it usually just flies through so fast you don't have time to read it.

Over the weekend I was applying Windows updates and got a BSOD. Couldn't get back to Windows... it would BSOD each time Windows started to load. Decided to roll back to my last backup, but it couldn't even load Windows off the DVD to get to the repair/restore screen... BSOD. Didn't know what to do, so I went into the BIOS to check settings. Everything looked fine. Just for kicks, and not being able to think of anything else to try, I reloaded my saved settings profile even though settings were already correct. Then it was able to boot into Windows off the OS drive, and then I went ahead and did the restore anyway, which it did fine. Reapplied Windows updates fine, and made another backup point. Fired up P95 on blend, and it's been going 12 hours.

At this point I could try updating the BIOS (still using initial version) and updating the Intel Matrix Storage Manager driver. But I'm wondering if that's just a waste of time. The pre-OS pausing and freezing during AHCI port detection couldn't be a result of the driver. Losing track of my OS drive in the BIOS and making the storage drive primary wasn't the driver's fault. Not being able to load Windows off the DVD wasn't a result of the driver. Looking at the release notes for each of the new BIOS releases, they appear to only be updates for new CPUs. And even if my BIOS was causing the BSOD under Windows, it shouldn't be losing track of the OS drive, or freezing during AHCI port detection, or preventing an OS from being installed off the DVD without reloading settings. There just seems to be something flaky with the mobo.

So... if you were in my shoes, you would spend any more time on it, or just avail yourself of the 3-year warranty? Does anyone think there could be something else going wrong that I'm missing?

Thanks in advance for your help.