Well, I've been reading sites and watching informative videos, coupled with the evidence being given to me by my system...and I've really come to three conclusions.
1. The PCIE-AGP bridge is AGP 8x only and locking up MB during POST.
2. The x700 is pulling too many watts and the MB is refusing to POST with the available Amps on the 5V rail of the PSU.
3. The x700 card is somehow dead and locking up the system, preventing POST.
Now I've tried powering everything on at 25 Amps by removing the DVD-ROM, ZIP, and Hard Drives to reduce power draw. I'm wondering if the Barton core is pulling more watts than my Palomino core did. I'm wondering if putting the Palomino back in will reduce current draw and get the system to POST with the updated card installed, just to see what happens. I'm also going to pull one of the 1GB RAM sticks out, dropping the system to only 1 memory stick. Might help with power draws. I kinda wish I had one of those 45 Amp PSUs to try on this system. That would at least rule out #2 if it still refuses to POST. I also don't believe #3, because even if the video card is bad, I'd usually get a Beep Code from the MB during POST, saying no VGA installed. I'm going to be going through all the hardware I have available to see if I have ANY PSU with more than 30A on the 5V rail today.
EDIT: Ok, so I tried everything out of the system, including the RAM, so it was just MB, CPU, and x700 card. At least I got a beep code this time - the NO-RAM beep code. Put one stick back in, no response. In fact, I'm noticing that the x700's fan doesn't immediately start up at full-speed. It turns on and off, almost like the card simply doesn't have the juice to fully start-up. That's with the 25A 500-watt PSU.
I broke apart my Pentium III Voodoo2 SLI system and it has an older Pentium 4 ready 350Watt PSU with 30A on the 5V rail. I used THAT...same story.
I pulled out my old 1800+ Palomino CPU and swapped the CPUs out and reset the CMOS. Same shit. So I'm going to assume at this point that the x700 is simply not receiving enough power and that MAYBE you're right, but I don't have anything with more power than 30A on the 5V line. Just putting in the 9550 back in and the system fully POSTs and starts up into Windows XP (when the HDD is connected, of course).
So if it's a power-draw issue, wouldn't the 9800 Pro pull just as many watts, if not more? Wouldn't it also not start if I got one? What about a new PSU? Newegg has a Logisys for under $20 that's 550 Watts, but has a whopping 38A on the 5V rail.
https://www.newegg.com/Product/Product.aspx?I … N82E16817170019