Background
I've been having a peculiar problem with Vista. When I initially installed Vista, the system was 100% stable. I then decided to enable power management to reduce power loads (i.e. I changed the power options from Performance to Balanced). That seemed to work well, but I noticed the computer was only using S1 sleep. I enabled S3 sleep in the bios, and afterwards the system crashed everytime it attempted to exit standby. I traced this to a 'S3 video post on resume' option in the bios that was ON, but needed to be turned OFF for things to work. Once I corrected this, things seemed ok.

Problem
I then started to notice spontaneous resets were occuring, at intervals of ~8 hours. I'd leave my computer and return to find it had reset. The event log noted 'unexpected shutdown', but was otherwise uninformative. This puzzled me, so I experimented a little.

Investigations
I noticed, of all the devices installed, my SB Audigy 2 was behaving rather erroneously, with crackles, pops and cut-outs. It had done so for a while (since a Creative driver release in May), but I thought perhaps it was experiencing power-related inconsistencies. Since it is the oldest component in the system (4yrs old), I though to disconnect it. Onsodoing, the internal sound device was enabled and the sound was fine. The system however still continued to crash, but the nature of the crashes changed. They now stated in no uncertain terms (via the good ol' BSOD) that there was a MEMORY_MANAGEMENT error, probably related to a new device/driver or to bad memory. I ran the memory diagnostics tool twice, but this revealed no errors with the memory. I updated all drivers to no avail. The computer crashed randomly at approximately 8 hour intervals, whether I was using it or not. It could happen outside OR within standby (a clue that suggested to me the problem was power-related, rather than software-related). I then experimented with power option settings. I have found the crashes appear to NOT happen when the power setting is 'always ON' (performance) (the computer has now been on 70 hours without incident). I think this may be related to the Intel Speedstep being OFF, and somehow this confers greater stability.

I thought it might thus be a BIOS problem and updated my BIOS to no avail. The crashes could and still happened.
Questions
Is it the PSU?
From the pattern of things, the first thing that comes to mind is a PSU problem. My PSU is however ~550W (can't remember the make) and was bought to replace a previous PSU which had failed and fried the motherboard in the process. It is thus only ~6 months old and is unlikely to be the cause. Details of the rest of my system follow.

Is it the motherboard?

Is it the processor?
Has anyone else noticed this with Intel Core2Duo processors and Vista? Or is this a configuration-dependent issue?

System details
AIDA32 © 1995-2004 Tamas Miklos

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Version AIDA32 v3.93
Author tamas.miklos@aida32.hu
Homepage http://www.aida32.hu
Report Type Report Wizard Pro/Lite
Computer RICHARD-PC
Generator Richard
Operating System Microsoft Windows Longhorn Home Edition 6.0.6000 (Longhorn Beta)
Date 2007-11-15
Time 00:50


Summary

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Computer:
Operating System Microsoft Windows Longhorn Home Edition
OS Service Pack None


Motherboard:
CPU Type Intel Core 2 Duo E4300, 1800 MHz (7 x 257)
Motherboard Name ASRock 775I65G
Motherboard Chipset Intel Springdale-G i865G
System Memory 2048 MB (DDR SDRAM)
BIOS Type AMI (05/28/07)

Display:
Video Adapter NVIDIA GeForce 7800 GS
Monitor LG L1710B (Digital) (130863659)

Multimedia:
Audio Adapter Intel 82801EB ICH5 - AC'97 Audio Controller
Storage:
Disk Drive Maxtor 6V300F0 ATA Device
Disk Drive ST3200822AS ATA Device (200 GB, 7200 RPM, Serial-ATA/150)
Disk Drive USB 2.0 Flash Disk USB Device
Disk Drive WDC WD1200JB-00DUA3 ATA Device
Disk Drive WDC WD20 00JD-22HBC0 USB Device
Optical Drive DC4517M BCT223P SCSI CdRom Device
Optical Drive HL-DT-ST CD-RW GCE-8520B ATA Device (52x/24x/52x CD-RW)
Optical Drive HL-DT-ST DVDRAM GSA-4163B ATA Device


Input:
Keyboard Microsoft USB Office Keyboard (IntelliType Pro)
Mouse Logitech HID-compliant G3 Laser Mouse

Network:
Network Adapter Bluetooth Device (Personal Area Network) #4
Network Adapter D-Link AirPlus DWL-G520 Wireless PCI Adapter(rev.B) (192.168.1.64)
Network Adapter Realtek RTL8139/810x Family Fast Ethernet NIC
Modem Sony Ericsson W950 USB Modem