Problem with Radeon 5870

I just bought a MSI R5870. I am planning on using it in a new rig that I will be building in the next week or two. I ordered it early because they appeared to be moving quickly.

I arrived today and I decided that I should test it to be sure that it was not DOA.
To test it I put it into my current rig. When I fired the system up I got nothing. My monitor stayed blank and there was no sync signal (indicated by an orange led on my monitor). The BIOS however did NOT sound any error beeps.

This rig is older and under powered so I had not expected the 5870 to perform in a 3D application but I figured that it should at least display the post display and windows startup.

The specs for my current rig are:
Athlon x2 dual 4400+
ABIT AN8 SLI
2 GB RAM
420 watt Thermaltake psu
Dell 2408FPW Monitor

There are a two items that I suspect might be the issue but I am not 100% sure on them.
First is the PSU. MSI stated that the 5870 requires at least a 500watt PSU.
This older rig only has a 420watt psu. I remember when video cards first started requiring power connections they would still run with less power than 'required' and would boot to windows but would simply crash back to the desktop if you attempted to launch a 3D application. Its this no longer true? Is 500watts a hard requirement which must be met?

Second, I am unsure about my "SLI" motherboard. This board should be capable of working with a single ATI video card, right? There is a "SLI Mode Switch" on this motherboard. I tried booting with this key set to "normal" and I tried without the key at all.

If the card is DOA I want to get it RMAed a quickly as possible so that I can get a replacement.

I would appreciate any advice or suggestions.

Ya, I figured that would be the case. My previous card had 2 DVI connectors and behaves just as you have described.

I have 2 monitors. I first tried monitor #1 on the top DVI, then monitor #1 on the bottom and then monitor #1 in the top and monitor #2 in the bottom.

The results were always the same. The monitors which were connected would indicate that there was a DVI cable connected but there was no sync signal.


Oh, and I figure that I should mention that:
...I did reseat the video card 4 or 5 times.
...I did return my original card (MSI 7900 GTX) and all of the displays worked fine.

Why on Earth would you buy a HD5870 for that system? Why not upgrade the system first. I mean cmon, 420 thermaltake psu? 2gb of ram? 4400+??

I think your system is DOA, not the video card.

My new system components arrived earlier this week and the build went smooth.

This card is running perfectly in the new system which is powered by a 800watt BFG PSU.

Thanks for all of the input everyone.