Most of the set-up is 18 months old. I run: K8N Neo Platinum motherboard AMD Athlon 64 3000+ CPU 2 sticks of Kingston PC2700/333 (512mb/each) 2 WesternDigital 120gb SATA drives Raid0 1 Seagate Barracuda IDE 160gb I use only for backups nVidia GeForce 7800GS video card (4 months old), Dual display LCDs connected M-Audio Delta 1010LT sound card (1 month old) My power supply came with my case, made by Just PC USA Inc. It's a 450W. For the last few weeks I've been having random restarts. Sometimes I get a BSOD, othertimes everything just powers down and restarts with no Minidump being created. I don't do any graphic-heavy computing (definitely no high-end games). Most of my time is dedicated to audio production. I run Ableton Live with Reaktor VST plugins, though sometimes I get a restart while simply browsing the internet. Sometimes I leave the room with nothing running but Windows and when I come back 5 minutes later I'm at my BIOS password entry. I ran Memtest, which was unsuccessful. I have two sticks 512mb each. Running just one stick, I can run Memtest for about 15min before getting an error. The other stick shows errors after about 5min. While trying various configurations/ram slots, my random restarts were getting worse and worse. At one point I couldn't even power-up. Unplugging everything from the AC for 30 seconds was the only way I could get it to power-up again. Have we decided it's the PSU, yet? To make sure, I grabbed the 512mb stick from my brother's computer. Before the BIOS could even complete the initial memory test my PC was shutting down. After shutting down, the power LED on the front of my case was flashing. Does anybody suggest testing something else before replacing the PSU? Is there a reliable way to test the PSU? Finally, if my PSU has failed, how much damage could it have done to my components? Should I get a new PSU before replacing my RAM? (Do I owe my brother some new RAM? Any help/suggestions are much appreciated.