Asus Extreme nVidia GeForce 6600GT 128MB DDR3 SLI

Hello everyone, this is my first post at Tom's.

I was thinking about overclocking the 6600GT SLI I've got here since the next-gen games are getting a bit heavy on it. It's a single card; I'm not using the SLI option. There was no difference between the normal and the SLI version price-wise at my hardware store, so I picked the SLI version.

I got CoolBits and it says that my card is clocked at 500mhz core and 2ghz memory. 2ghz? Isn't that a bit much? I thought it was clocked around 1ghz stock? Anyways, I reject my warranty and I figure to let CoolBits determine optimal frequencies so I can start from there. I get something like 557mhz and 2,1ghz. Great! I press the "test" button and it fails. No problem, I reduce the clocks and... it fails again. Mmm. I set the frequencies to 501/2,001 and... another failure. So much for CoolBits. I disable it (and regain my warranty in the meantime; lmao).

I get RivaTuner and reboot the system to determine the clock frequencies. It comes up with a 500mhz core and 1ghz memory. That's a lot more likely, but why did CoolBits say 2ghz then? Which one of them is right?

Anyway, I start overclocking and I put them at 550 and 1,1. Reading articles on overclocking the 6600, I believe that those frequencies shouldn't be too much of a problem. I fail the RivaTuner tests so I decide to disable the test and see what happens. I apply the changes and I'm off.

Next, I start a game and in a minute or two I get purple artifacts flickering everywhere. The fps increase is only a 5-10fps, I'd be happy with that if only those artifacts weren't there. I check the temperature of the card through the ForceWare menu and it's at a reasonable 50-60°. I decided to go back to stock settings and write this post here.

So that's my first attempt at overclocking a GPU. I'm using stock cooling right now, but I don't think that should be a problem since the 60° isn't that hot for a 6600GT SLI. For the record, I'm not interested in getting additional cooling right now.

Can somebody explain to me what I'm doing wrong here? It's my first time overclocking a GPU and I'm eager to learn. I know I should go up in increments instead of going a immediate +50/100, but lesser frequencies aren't interesting if the +50/100 only give a 5-10fps increase.

I had the same problem with my 6600 became outdated. Sold it and got a x800gto, wich i have now and works perfect.

(My 6600 went from 300/500 to 550/550)

Well, it's an Asus and no, I can't swap it in.

Thanks for the replies, everyone. I think I'll just replace the card because I'll have to buy additional cooling to overclock it anyway.