Hey all

I finally got my hands on the Socket A parts I got already months ago and assembled them into a Chieftec Dragon Midi Tower.
However they are giving me some strange problems. Most of the time the system POSTs (it beeps and I can hear the regular boot sequence including floppy search and so on, I can also turn off an turn on the NUM light on the keyboard) but it doesn't output any video. Sometimes it outputs video (mostly when I hit the reset button a few times and/or power it off an on a few times) and most of the time when it THEN outputs video, the output is all yellowish. If the fullscreen logo is enabled, it has like corrupted, vertical lines all over the picture. These lines sometimes (not always) are also seen in the POST screen if the fullscreen logo is disabled.

hardware:
Asus A7N8X-E Deluxe
Geforce 4 Ti 4200 64MB and also Geforce 4 Ti 4400 128MB tested (have a Radeon X1950 Pro here too but the PSU doesn't have the 6 pin Power connector)
AMD Athlon XP 3200+ (also tested with Athlon XP 3000+)
3x 1GB DDR400 memory (CL2, CL2 and CL3), tested with each of them alone
big, fat, copper thermaltake cooler with fan
Some 300W (seems not too cheapish) PSU, has stickers on it which say "AMD recommended", "Intel P4 ready" and so on

It has been about 10 years at least when I hardware-troubleshooted a system like that the last time, what could be the issue?

What I could imagine:
- PSU too weak/cheap
- Motherboard defective
- both Geforces defective

Thanks for any advice!

edit:
Voltages:
3.3V: 3.32V
5V: 4.89V
12V: 12.41V

MB temp: 31°C/87°F
CPU Temp: 54°C/129°F

edit2:
oh my, i just found out that my VGA cable was doing the yellow color. I put in an AGP GF4 MX4000 and with that card the system is booting and POSTing flawlessly every single time. Also a voodoo 3 2000 PCI works. So now either both Geforce 4 Ti cards are faulty or the PSU isn't supplying enough power - what do you think?