No Video on new home built dream machine

I wanted to build my own ultimate dream machine. But it's turning out to be more of a nightmare. I'd like someone to wake me from this nightmare .

Contents of my Antech P-160-WF case

1 Zalman ZM400A-APF ................... Power Supply
1 Gigabyte 8KNXP ...................... Motherboard Rev 2.0
1 Intel P4 3.0 HT ..................... CPU
2 Corsair DDR 512 XMS ................. 1 gig of DDR RAM
2 160GB Segate ATA drives ............. Raid 1 Storage
1 Western Digital Raptor 76 gig SATA .. System Disk
1 Plextor DVD +/- RW .................. Only optical drive
1 ATI Radeon Graphics AGP video card ... no model number, 2000 build date, Part Number 109-78500-00
1 cheapo Floppy ....................... For legacy media

Problem
-------
No video
Tried two other video cards
Tried another monitor
Tested CPU
Replaced Motherboard

Still nothing at all on the monitor.

There is power to the CPU Fan, Chipset Fan, Graphics card Fan, case fans.

I plugged a device that draws power from a USB port, and there is power to all USB ports.

I'm out of ideas, any suggestions?

Is it possible that the power supply still could be faulty?
Could the graphics cards (AGP) be too old?

Thanks for any assistance you can provide.

Try the PSU with a different computer. Preferably another P4 one.

[Insert witty comment here]

Well, first of all, you might have blown the motherboard with that old video card. It might have been a 3.3v signal video card, and the motherboard is made for 1.5v AGP signals.

But other than that, if a PC turns on but doesn't show a screen, without a beep, it's usually caused by a flipped IDE cable. One guy said a flipped floppy cable did that to him as well, but I've never seen that one.

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