Problems booting AMD64 Dual Core

["I.E.Broadbent" <ieb@klokwurx.co.uk>]

I built two boxes last week...
both (almost) identical....
CPU - Both AMD Socket-AM2 64bit Dual Core (one 4300 and one 4600)
Memory - both identical - 4 x 1gig modules per motherboard
Motherboard - both identical - Gigabyte S-Series M61P-S3
Both using onboard Network and Graphics


One machine works fine.... no problems.... in fact superb fast and sweet
as a nut.

The other ... is a dog!
It wont output any display at all when all 4 memory slots are populated,
and when using only 1,2, or 3 it 'stutters' along working for about 40
seconds then locking up for 10 accepting no input and producing no
output.

I have exchanged the motherboard for another, making no difference
Have upgraded the BIOS to version'f' - no improvement
Have changed the power-supply (and enlarged) to ensure it's not a
voltage issue.

I even used different memory modules to see if it made a difference, ..
but it didn't.
 
The only thing I haven't changed is the CPU... but the supplier is
reluctant to swap it out .. claiming that if it is working at all (even
crippled) then it wont be the CPU at fault.    My claim is that it is
the ONLY thing left, and if the dual-core addressing has an error then
it might explain the 'stuttering' and the failure to boot when connected
to 4 modules.

Anyone have any comments or suggestions please.

Anyone heard of any problems with the CPU's or Boards mentioned above?

Thanks, Ian