Here's the situation:

I got a 5770 yesterday. If I put it in my computer, the computer halts booting at C1 (memory error) regardless of whether or not it has extra power. There are no beeps.

If I put my old video card in, it boots fine (most of the time, I think my motherboard is getting old). If it has no power, I get beeps.

If I put both video cards in, the computer halts at C1, regardless of which slot I put it in.

I took it into a store, plugged it into a computer and gave a post beep (the good kind), but couldn't get any video out of it.

Should I try another computer, or just RMA the 5770 now? My motherboard is 4 years old now, and the fact that the second computer got a post beep worries me a little.

RMA the 5770.

Nearly 2 weeks later:

Get a new 5770. Same problem. Look it up online. Apparently this has happened to numerous people. The 5770 is isn't inherently backwards compatible with PCIE 1.0. The BIOS needs an update to be able to handle it. Yay for me getting convinced to buy DFI, who has quite possibly the worst website of all the motherboard manufacturers and a very poor support system. From what I hear, they simply do not support old tech. This is the last time I spend $200 on a motherboard.

Looks like I'm going to buy a new motherboard/cpu/ram combo to get this thing to run, then give my old stuff to my mom, whose computer is dead.

My Asus M3A78 Pro is a little over 2 years old, but has had several BIOS updates, with the last one so far having been released just a little under a month ago (for new CPU support). Based on the numbering, the latest one is the 16th revision, though they don't seem to have released some of the revisions.

I think I was trolled into buying DFI, or DFI became a bad company after I bought them.

During the capacitor crisis of a few years ago (see badcaps.net), I think DFI was pretty good in their quality, and superb in their overclocking, which is why I got the motherboard. Looking back on it, this was pretty stupid: I spent $200 on the motherboard, $200 on the graphics card, and $185 on the processor. Now DFI may have quality parts, but they refuse to update their old stuff, and I have had nothing but trouble with their site. Biostar, a known to be somewhat shitty motherboard manufacturer has an excellent site. It doesn't look like they have updated their BIOS on the old nf590 though. I know gigabyte and asus both are excellent and do support older stuff. More power to them.

I grabbed a Gigabyte 870A motherboard, with 2x2 GB of OCZ ram (which has terrible reviews, but it was $25 off), and an athlon II x3. Not bad for $213. It will be here around the 3rd-5th, and I'll finally be able to test my graphics card.