Overclocking the processor won't impact your GFX card's performance. You can overclock the card separately using Riva Tuner.
What do you mean by the GFX card not performing like it used to?
I've been running my E6600 as 3GHz for the last 3 years without any issues. I basically followed the advice here:
http://vip.asus.com/forum/view.aspx...P&id=20071005044049234&page=1&SLanguage=en-us
I can't find a similar thread with the BIOS screens for the P5P41C and the Asus forum has very little content for this board. Are they anything like the P5B Deluxe in the link above?
In order to run a stable overclock with the E6600 I've found that the processor doesn't need a lot of Core volts, in fact it's stable with below the default voltage for running at stock. I have it set to 1.2875 at the moment in BIOS, which equates to 1.24 in CPU-Z. As you probably know, the lower the voltage the better as voltage equates to heat and too much heat will damage the processor.
My advice would be to do things in this order:
Ensure that you have a recent BIOS installed (don't update within Windows).
Download and install the latest versions of CPU-Z, Orthos and Coretemp
Check your temperatures are OK running at stock (CPU should idle below 50 degrees). If temps are high it may be down to dust in the case.
Increase the FSB slowly and check stability each time by ensuring you can boot and then run Orthos blend test. When you have the desired overclock, reduce Core voltage to minimum required to be stable (no errors in Orthos for 12 hour run).
You can also check stability of RAM by running MEMTEST (runs from CD on boot).
You may need to lower the DRAM frequency as it steps up with the FSB on the P5B Deluxe, not sure if that is the same with your MB.
Do you have the stock cooler?
Lawrence
