My spec is in my profile, but I will also list it here.... I just noticed today that my RAM was running Single Channel mode, so I thought I would change it to Dual Channel mode... so I did. It completes the Windows XP loading screen, then reboots... constantly, until I change it back to Single Channel mode. Is there something wrong with my RAM? or is it the motherboard? or my PSU not giving the mobo enough power? I dont have every power cable plugged in, I have a 20 pin ATX power in the 24 pin plug, and the 4 pin ATX power plug and a 4 pin molex cable plugged into the motherboard. Could this not be giving it enough power? Many thanks, system spec = AMD Athlon 64 4000+ DFI Lanparty UT nF4 Ultra-D 2 x 512mb Crucial Ballistix PC3200 DDR400 Connect 3D X1800XT 256Mb 2 HDD's etc. Antec TrueBlue 480W PSU.