SLI-DR Expert/A64 3800/Ultra X-connect problems

[Bizznatch]

I'm having problems with my new setup. Here are the specs:

DFI SLI-DR Expert
Athlon 64 3800 (939)
Ultra X-Connect, Version 1, 500w Power Supply
eVGA Geforce 7900gt signature edition
1GB (2x512mb) Kingston HyperX PC3500, in DIMM slots 2 and 4
Plextor DVD Burner
Western Digital SATA Hard Drive
Floppy Drive

The Ultra X-Connect is the first edition and I'm using a 20-24pin motherboard adapter as well as a 4-pin to 8-pin CPU adapter. Also using an Ultra X-connect brand 4-pin molex to 6-pin PCI Express cable.

All the parts are new except for the motherboard, which I picked up as "Open Box". The Power Supply was pulled from my previous computer, it was only a few months old when I took it out and was working fine when I did.

Everything seems to power up fine. However, i'm getting a bunch of different types of problems during boot. All of which are tempremental but I havent gotten it to cleanly boot once.

It will either:

1. (most common) System will boot fine, it will not try to boot from the floppy disk which has a brand new bootdisk I just made in it, or the DVD drive which has a copy of windows XP in it, no matter what boot priority I set it in BIOS it wont boot floppy or DVD drives at all, it will try to boot the Hard Drive, which has a fresh install of windows on it, but when it goes the the desktop the system will shut down.

2. the system will shut down shortly before the POST beep.

3. System will shut down shortly before Windows boots.

Also, right after it shuts down i'll press the power button and nothing will happen, but the yellow/orange lights on the motherboard are still on. If I flip off the switch for a short period of time then turn it back on it'll power on and try to boot, but it'll keep doing the same as #1 or #2.

Things Iv'e tried:

- Ive tried not using the 4-pin to 8-pin CPU adapter, like it says in the manual. but the same thing happens either way

- Ive tried just about every compbination of DIMM slots to place my RAM.

- Ive tried taking all the components out of my PC case and plugging them all together on my table (to see if the motherboard or some other component was being grounded).

Ive also narrowed it down to 2 possible causes: the Motherboard itself, or my power supply.

I need to know which one it may be, so I can either return or RMA the motherboard, or get a new power supply.

[Gilly]

by shut down you mean literally turns off? and does the psu need turning off before the system will power up?

[Bizznatch]

yeah it was powering off by itself, doesnt matter though, I figured out that DFI LANparty type motherboards dont like the 20-24pin PSU adapter being used.

I Bought an OCZ GameXStream 600w today and the system works fine now, except I cant get it to boot from floppy so i can fdisk the drives.