Overclocking a 4650

[Nilushan]

I have an HIS 4650 512MB Graphic card. I overclocked it from the Catalyst Control Center.

GPU Clock - Default=600 OCed @ = 700
Memory Clock - Default=500 Not Oced

When i play Battlefield 2 on default settings it runs fine. But when i overclock it even a little bit, it lags.

And i run 3DMark Vantage. Upto 700 on the GPU clock it runs fine. But when i increase more everything gets stuck. Why?

And this card doesnt have a fan. Instead it has a Zalman isilence4 heatsink. In Catalyst Control Center it shows that a fan is working. And it even shows the fan speed %. Why?

 

[toxict51]

i might not be able to help u but im gonna tell u a similar thing that happens to my 9400 gt (inno3d) i play at stock better than when i OC when i OC it gets weird but when i leave em at stock it plays better i posted a thing abt this idk when they will reply gd luck to us i guess

 

[shubham1401]

Can't tell about Fan problem.

But every card has its OC limits.
Are the lags like Glitches with looping audio?
If yes then reinstall drivers and run it at stock clock speeds.

Same thing happened to my old card when it was OCed even a lil bit.