Problems with K7VTA3

Archived from groups: alt.comp.periphs.mainboard.elitegroup (More info?)

I have a new system with the K7VTA3 mainboard, an Athlon XP 2600+ and 2x 256
MB DDR-RAM (400 MhZ, CL3).
I have this additional hardware: Cybis Geforce FX 5700, 2 harddisks
(connected to secondary IDE) and 1 DVD-ROM and 1 CD-RW (primary IDE). I
checked the jumpers again; they seem to be set right.
OS: Windows XP.

Now all programs I use keep crashing (MS Outlook, Mozilla and Windows
Mediaplayer so far) after some time (I had to write this thread offline). If
the computer is working hard (while installing programs etc.) it resets
itself; this does not happen if the system is idle.
I can imagine several reasons for that problem:
1. Not enough power (this would at least explain the system restarts). The
total power output however is 300 Watt maximally and I was told this is
enough if I do not have too many devices connected.
2. Some damage to the mainboard?
3. Incompatibility of components?

The strange thing is that a friend of mine bought the same mainboard, CPU,
RAM and the same Geforce (though of a different brand). He has even worse
problems, he is not even able to install an OS because the system keeps
telling him this or that file could not be copied to the HD.

Cheers,
Matthias