Overclocking my 6600GT for you know what

So anyway I've started fiddling with overclocking my card ready for when I can afford Oblivion. I'm using Coolbits and I've clicked "Detect Optimal Frequencies". The core clock jumps up to 348 MHz from 300, and the memory clock to 991 MHz from 900.

I left it at that and played CoD2 and was blessed by what can only be described as chunky strips of rain and having my hands seeming strung together and holey. Oh and I get the occasional strip of texture across a battlefield. Mmm, strippy.

Now I kinda expected this because I've read the CoD2 is quite sensitive to overclocking, but HL2 and the CS:S Video stress test run without any graphical artifacts.

Is it just CoD2 being overly sensitive or am I over-overclocking?

EDIT: Apart from the graphical anomalies I'm getting ~20 FPS higher, which is, y'know, nice.

20fps more than what?
20fps more than 200 is not worth risking your hardware for.
20fps more than 20 might be, but I'd be very scared about the heat you're generating when you're pumping that much more data through the thing.

Jwenting has a good question, what is your fps before overclocking on oblivion?

This kind of increase will shorten your card's life if you aren't adding extra cooling. How's your case cooled? I recommend bringing the core down to 330 to follow the 10% rule

Oh I learnt that the hard way. Imagine major graphical artifacts then the first bluescreen I've had since I've had this system.

It's all running well now though and I've put the settings back to factory defaults until tomorrow when I give everything it's weekly de-dusting and when I've got more energy, I'm completely wiped.

EDIT: I meant 20FPS more than my usual 25 in CoD2 directx 9 most settings maxed out 1024x768.

One of my friends was talking about switching to DX7 instead of DX9 and he got some 80+ FPS on top of what he was getting before. He says there isn't much graphical difference.

I don't really know how or what he did.

When I used to play with Ogre3D a black screen alone would make
7 > 9 > OpenGL

Make it a game-like scene and
9 > GL > 7

Maybe the game he was playing wasn't very intense graphically
Also a lot has changed from DX 7 to 8. 9 added pretty shaders
A graphics intense game wouldn't look so good in 7

Running a DX7 application under DX7 instead of DX9 might give higher performance.
Problem of course is that you can't then run any DX8 or DX9 applications on that machine anymore.

I know about running in DX7 and I've got no problems with it, except the water looks absolutely disgusting. I mean in CoD1 (which was 8.1) it looked ok, CoD2 w/ DX9 looks alright too, but in DX7 it's just blue mass and looks really out of place.

Still a great game though.
Well it looks like I'm not going to get much more performance outta my card for Oblivion :(