I have a Soyo 6VCA m/b with a Herc geforce256 DDR vid card in a system that has been rock solid for over a year.  The other day the I came home from work (had left the system on) and my screen showed no keyboard present error on bootup.  I am the only one that uses my computer, so not sure why the reboot during the day.  I restarted the computer, and it worked for a bit, then did a hard lockup on me...no keyboard, no mouse, had to hold the power button in for 5 seconds to shut it down.  Restarted, worked for a bit, then same result, restarted one more time and only got a black screen..  

So, in troubleshooting, I reset the CMOS jumper to default it, and still no go.  I then proceeded to pull all components, including motherboard, thinking that perhaps the m/b was grounding out, and still no go.  I then pulled out my old RIVA128 TNT STB vid card, put it in, and it worked, booting up to bios screen.  So I determined there that the Herc DDR vid card was wasted, and went out and got a new GeForce 2 MX400.  Came home and put that in the isolated m/b, and no go on the new vid card.  I have pushed down as hard as possible on both the geforce cards trying to seat them as good as possible, but to no avail.  

I am now at a loss as to what to do.  Any suggestions would be appreciated.

Thanks in advance for your help.

Other components in system:
550e P3 o/c'd to 770mhz  (105 mhz fsb)
SB Live Value
10/100 NIC
384 mb ram

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