"kony" wrote in message
...

Instable memory should not turn off the system in 4 seconds,
it would merely fail to post or crash.

This kind of problem is more often one of two sources:

1) PSU itself isn't staying within accepted voltage ranges
and shuts off. Might be defective, might be powering
defective parts, or a general system build error has shorted
something (doubtful since it stays on 4 seconds).

The PSU might be checked with a multimeter, monitored right
up until the point of shutdown.

2) Motherboard cause, either bios sensor reading out of
range (like voltage or fan RPM), or hardware shutdown like
CPU temp (particularly if heatsink isn't making contact- a
merely marginal heatsink installation wouldn't be bad enough
to hit overheat threshold within 4 seconds from cold-off
state, it'd have to be removed and the interface inspected
to determine this as 4 seconds isn't likely enough time to
get to the bios health monitor page to see any readings.

-------------------------------------------
Although I'd more likely concur with older chipsets, DDR2-based boards are
increasingly picky about memory. When the NFORCE430 and P965/G965 chipsets
were first released, I had problems with some custom builds, whereby the
system wouldn't reach a POST screen, but symptomatically power on, then
power off in a never-ending cycle every 3-4 seconds until memory was
exchanged for more compatible sticks, immediately solving the issue with no
other component or settings changes. Since the OP was mentioning identical
symptoms, and is using memory out-of-spec for his board, I suspect memory
being the culprit.

Russell
http://tastycomputers.com