5770 and 5830

maybe the cards are overheating and drawing too much power from the psu. the 5830 is a known dud card. it produces more heat and uses more power than the next level card (5850) and gives less performance. get HWmonitor to monitor temps and get back to us with results. If the temps are fine try another driver. Also what PSU do you have? maybe its failing to produce enough power. If i were you id sell all of your cards and get a faster single card. You could sell them all and get a 5870 or 6870.

My PSU is an Etasis 750w, which makes some PSUs for Silverstone. I know the 5830s aren't the best cards, but that doesn't explain why the 5770 was having the same problem. I've been monitoring temps with GPU-Z, and have had crashes in the 55 degree range.

you said 1 ram stick is bad. have you removed it from your computer? id say thats the problem. Either its still in your best interest to sell all the cards and get a better single card.

The bad RAM is out, yes. I'm not looking for advice on how to change my build, I'm looking for advice on how to fix my problem. For the price I paid, I'm happy with the power and performance I'm getting, except for this issue.

Are you familiar with driversweeper? Download driversweeper and follow ALL the instructions to remove all existing ati drivers from your computer. now Download the latest driver and install it.

it's a clean install, so the only driver that's ever been installed is the current one. I did some tests on my own, and it looks like the PSU was the issue - it's not pushing enough power to supply everything when the GPU(s) come under load, even though temps aren't an issue. I need to test the PSU that I think is defective in my other PC, that currently has the 5770, but when I swapped PSUs into my main PC, everything worked fine under heavy stress. I also removed another DIMM, so there's only 4GB in there now, the bad one and its mate are out. They're going to go off to RMA at the same time as whatever other components I have to send off - hopefully my PSU is still under warranty. Thanks for all your help.