No video. No POST.

I'm attempting to diagnose why there is no video display on a T6420 Emachine, running Media Center OS.  The CPU is an Athlon 64 3400+ and the memory consists of two sticks of 512 Mb DDR2 SDRAM.  Video is entegrated on the MB.  I've done the following:  (a)  Installled new PCI-E video card.  No change.  (b) Removed modem & disconnected HHD & Optical drive.  No change.  (c)  Tested power supply. Showed to be okay.  (d)  Replaced power supply.  No change.  (e)  Inserted PCI POST diagnostics card.  All circuits are lit, as though they are functioning, but no codes whatsoever show on the display.  (f)  CPU fan & case fan running well.  (g)  Changed to a known working monitor.  No change.  Any suggestions?
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AndrewCinkConnect With a Mentor Commented:
I'm leaning towards CPU or motherboard. I would be guessing motherboard first. See if you can beg/borrow/buy one and try changing it out. If it's not the motherboard, then it's very likely the CPU. Just to be safe, you could try running it with only one stick of ram just to see if it's different, but I doubt it will be.
Hello John_1:

With the POST card and no codes I'm betting on the CPU.  Most POST cards I have used run thru a series of numbers as the BIOS does its POST routine, so no numbers = no brains = no CPU.

As a last gasp try pulling one of the RAM sticks.

FInally, are there any beeps? (assuming speaker is connected)

Try remove the coin shape battery out of the board for 10 minutes see if any improvement?
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A lot of emachines boards had problems with bad capacitors.

<A lot of emachines boards had problems with bad capacitors.>

Well said - and with a lot of other things, too!  

They are usually near/at the bottom of reliability rankings.

You might be beating a dead horse there.

John_1Author Commented:
To warrenbucles:  I did pull each memory stick and test. Result: No change.  I also inserted a known good memory stick.  Result:  No change.  Are there any beep codes?  No.
To Punky:  I removed the cmos battery, as you suggested, and replaced it with a new one.  Result:  No change.  I didn't think that could be the problem, however I didn't want to leave any stone unturned.
I am awaiting the arrival of a new CPU.  We'll see what happens, then.
Thanks for the input, guys!
I agree with the above comments that the CPU is bad.  If you have a way, could you check current CPU on another machine with the same Socket type.  That may explain the fundation of your problem.
John_1Author Commented:
Sorry for the long delay, guys.  I finally acquired another CPU and motherboard.  It turned out that the original CPU is still good and the board was bad.
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