On overclocking GPUs

[pirahna1]

On overclocking GPUs.

So I currently have this (http://www.newegg.com/Product/Product.a ... 6814127286) video card. It's an MSI NX8600GT (256mb 128-bit GeForce 8600GT). MSI packs it with a feature called D.O.T (Dynamic Over-Clocking Technology) which offers 6 levels of Core and Memory Clock over-clocking. I currently have it at level 6, which is 10% over-clocked. MSI says this is safe and runs stable, which it does.

When I play games (NFS: PS, CoD4, Crysis, etc) my card can get up to 60 degrees Celcius, idle it runs at about 41 degrees Celcius.

When I try and over-clock it even more (I only tried a 5% increase) my games will load with sound but no graphics. I figure the card isn't capable of going over 10%. Is this a safe assumption?
Right now I'm running stock cooling, but I was planning on buying a PCI slot fan to blow cold air over the heatsink/stock fan. Should I even bother with the fan? I can't get a reading on how hot the card gets at 15% OC, so I'm not sure if it's getting too hot, or if the card is just incapable of going over 10%.

Any opinions or help would be awesome. I plan on getting a 8800GT in about a year or two, once they get down to about 100$, so if I can't OC this card anymore, I'll be fine till then. I just wasn't sure if a slot fan would help any. Thanks!

[Avanarius]

It's hard to say what prevents a graphics card from overclocking any further but it may be some sort of conflict with the application you're currently using and manually doing it. If you're not already using Rivatuner I would give it a shot and see what results you get.

I really don't think it's getting too hot as the core shut temperature for most of those cards is above 80c. Toasty but it works. Usually stability is the first problem you encounter much before temperature becomes an issue with overclocking a video card as you can't use software to increase the voltage on most cards.

[pirahna1]

I'm using the installed program that came with my card (I'd imagine its just NVidia Forceware, but I can't find a name for it). I think MSI said the card can be overclocked to 10%, but the sliders go waaaay up, to like 50%. But the D.O.T feature will only allow 10%, but I disabled that when I tried to go 15%. I'll grab RivaTuner and see what results I get from that.

EDIT: Just ran RivaTuner and tested my card at 15% OC. Came back that the driver wasn't able to support the OC level. Oh well, least I know now