Take a very good look at your PSU - it could be putting out enough power to drive the 4780 but not the 5870. There's no way two cards in a row would have such a strange issue.Also, I've used compressed air to clean out computers for well over a decade (including in a professional repair shop) now and have never ever damaged one doing it. I'd be much more wary of sucking things with a vaccum than using compressed air.

Take a very good look at your PSU - it could be putting out enough power to drive the 4780 but not the 5870. There's no way two cards in a row would have such a strange issue.Also, I've used compressed air to clean out computers for well over a decade (including in a professional repair shop) now and have never ever damaged one doing it. I'd be much more wary of sucking things with a vaccum than using compressed air.

This is turning out to not be such a unique problem, I guess. I've just started to find a lot of posts about this issue and interestingly enough, none have any solutions -- just a lot of confused consumers! Seems I'm not the only one with this problem --and it's sounding more and more like some sort of hardware compatibility problem. My stumbling block with that logic, though, is that it worked so well for those 3 months. I've tried everything and it just won't display. One last shot tomorrow at uninstalling all drivers and reinstalling and we'll see what happens.

Also, I've used compressed air to clean out computers for well over a decade (including in a professional repair shop) now and have never ever damaged one doing it. I'd be much more wary of sucking things with a vaccum than using compressed air.

I agree! The static coming off a vacuum . . . scary! But also the use of compressed air has been "controversial" for years - some do, some don't. All I know is it seems every time I personally buy a can and use it on a computer I have nothing but (major) problems. I ended up buying one of these, << http://www.amazon.com/WD-40-Turbo-Air-Blow...mp;sr=8-2-fkmr0 >>but the airflow is not nearly as penetrating as compressed air which I thought would be more effective on a big, closed card like the 5870.

Agreed, symptoms say its time to look at the PSU. Though everything was fine....its not that uncommon.

FlyingBits: Looks like you and TechGuyMax nailed it. I went to BestBuy and bought a bigger BFG 1000 Watter and all seems ok! I didn't think that BestBuy sold PSUs that big and the only thing left that I could do for now was try the other manufacturer's card that I ordered Thursday night and is already in the mail. I'm glad you guys were so insistent. Motivated me to look on their website and sure enough their nearby store had one in stock. I bought the BFG and a "comparable" Rocketfish -- the Rocketfish was 70 bucks cheaper than the BFG! -- and the bottom line is the BFG did the trick, the Rocketfish didn't. It would appear that not all power is created equal, either, eh? I guess my 4870 was drawing wattage right up to the old PSUs limit and then when I put the water cooler in, the combination of the new pump and the 5870 took it over it's top limit -- even though my power gauge only showed about 350 watts being drawn on a 750 watt power supply. Like a bad pilot, I was fully focused on and completely trusting my instruments, so NO WAY it could have been the PSU. :( Thanks to you both! I really appreciate your tenacity and hanging with me --

FlyingBits: Looks like you and TechGuyMax nailed it. I went to BestBuy and bought a bigger BFG 1000 Watter and all seems ok! I didn't think that BestBuy sold PSUs that big and the only thing left that I could do for now was try the other manufacturer's card that I ordered Thursday night and is already in the mail. I'm glad you guys were so insistent. Motivated me to look on their website and sure enough their nearby store had one in stock. I bought the BFG and a "comparable" Rocketfish -- the Rocketfish was 70 bucks cheaper than the BFG! -- and the bottom line is the BFG did the trick, the Rocketfish didn't. It would appear that not all power is created equal, either, eh? I guess my 4870 was drawing wattage right up to the old PSUs limit and then when I put the water cooler in, the combination of the new pump and the 5870 took it over it's top limit -- even though my power gauge only showed about 350 watts being drawn on a 750 watt power supply. Like a bad pilot, I was fully focused on and completely trusting my instruments, so NO WAY it could have been the PSU. :( Thanks to you both! I really appreciate your tenacity and hanging with me --

Never Give up, Its not science, its computers!Glad your back in business, round of beers for everone... :(

Just to set the record straight, this was not a PSU issue or the result of the use of compressed air -- I'm on my third 5870 and third PSU, all from different manufacturers. The same behavior is exhibited as in my original post. I've gone as high as 1250 Watts and have tried everything I can think of, and everything suggested. The only bright spot is that I will be able to recover all of my costs (less some trivial shipping charges) via my vendor's outstanding return policies.Just wanted to record this for future posterity should anyone else be frustrated by the same issues.

Tried another mobo yet? That's the only likely culprit at this point.

Tried another mobo yet? That's the only likely culprit at this point.

No, not yet. That and putting the old e8500 back in is all I've got left to try, though, and I don't know if I'm willing to do either of those yet. My system with the 4870 runs smooth as silk and the 5870 is nice, but it's not nice enough to build a whole new system around yet. :( What would you recommend. If I were to replace this board, which is not entirely out of the question I wouldn't mind going as high as $300.

I've been buying Gigabyte EP45-UD3L boards for the past 6 months now, using 3 of them altogether. Great overclocking boards with decent voltage regulation. Micro Center seems to have them in stock @ < $100 for that whole duration.