I just upgraded my PC from a AMD athlon64 3400+ to a AMD athlon64 3700+ at first it ran hot but, I flashed the bios to the newest build and that got the temps down and after reseating the heat sink to about 45c idle. but now the pc reboots after about 5 mins of stress testing(I am running dnet or pcmark04) Full config of pc is as follows Abit KV8 Pro socket 754, AMD 64 3700+ 1mb cache, PNY Vertigo Geforce 6600GT agp 1 gig of cosair value ram, Antec Truepower 420 power supply 40 gig Seagate 7200 RPM, HD NEC 1300A DVD burner, USR 56k hardware modem (Model 2977), 1 80mm intake fan 1 92mm exhaust, and Zalman ALCU heatsink/fans onboth the CPU and Video card The system is currently running stable with the 3400+ installed again. No problems at all before I tried thenew cpu the system would run all day with no issues even during extended doom3 sessions. I am considering returning the CPU since the benchmarks I completed are almost identical to the 3400+. Any ideas to what is causing this my only guess would be heat but unfortunatly the Abit Guru monitoring software stopped working after flashing the CMOS, but no alarms sound for overheat or under voltage.