Please help...

[whywontitwork!?]

I apologise in advance for the length of this post, but please bear with me.

Hi there. This is my first real PC build, but I know a bit about computers. Right. Firstly, here is my setup:

Athlon XP barton 2800+
Thermalright SK6 w/Delta 60mm (one noisy mutha)
Gigabyte GA-7S748-L
256MB OCZ PC3200 EL
Sapphire Radeon 9500 128MB
Seagate 20Gb (working fine in this rig as I type)

The first time I connect it all up, the system starts, but no display and no POST. Second time, the same. So I took out the HDD, and it POSTs OK, but I cannot get into the BIOS, but the keyboard does work as I can make it attempt to restore from disk.

Connected it all up again this morning without HDD, and it POSTs OK again. Connect the Seagate, and success! Asking me if I want to start in safe mode of Windows XP. I say yes, and a long list of command lines scroll past, then stop, and the system reboots, but doesn't POST.

Now, the first time I plug it in without the Seagate, it POSTs, but only the first time, and still no BIOS. Following times, it doesn't do anything. No display. Nothing.

My first suspicions are the motherboard, but thought I'd try here before the long process of RMAing. Im pretty sure everything else works OK, as it POSTs, sometimes. Could also be the HDD, as its an OEM from my currnet machine?

Any help would be very very much appreciated!

[brad]

[whywontitwork!?]

[brad]

[whywontitwork!?]

[brad]

[whywontitwork!?]

[whywontitwork!?]