I doubt thats the culprit,he has a good PSU,I have a 9800 pro,barton 2500 overclocked to 2.2 ghz,2 hard drives(250 gig and 40 gig),one gig of corsair pro ram,cd burner,dvd-rom,floppy drive, Abit NF7-S mobo,and 6 LED case fans and my cpu fan all runnin on an Antec 350 watt PSU without any...
the battery wont matter if the pc is plugged into the wall,modern systems have a standby system, thats what the lights on the mobo are about.try flashing to a newer bios and see if that cures the crashes. any overclocking or anything going on?