My current motherboard and processor is a dual core pentium (E2180), at 1132MHz FSB, 10x (locked) multiplier, on an Asus P5N-E sli. 2.83GHz stable. I tried running at 1200MHz FSB, but it was unstable, and wouldn't even load windows. I know that it's possible to get more out of this processor. So, the two factors that I think are limiting me is either the northbridge, or cooling issues. Or possible cooling of the northbridge. Would getting a better motherboard possibly allow me to overclock even more? I was thinking of the Asus p5q:
http://www.newegg.com/Product/ ... aspx?Item=N82E16813131335

Of course, that board doesn't support SLI if I were to upgrade to SLI in the future. Which brings me to my next problem, which is what is the bottleneck causing my FPS to be low in GTA4. Is it the processor, or the video card? If it's the video card that is limiting me, then maybe I should not bother with a different motherboard, and just get a new video card. So many different paths I could take with this.

SLi sucks - don't bother.

The P5N-E isn't that good - the P5Q will get you more, but a second hand P35 might be better...

Another question, would it be better just to get a core 2 duo, and keep my old motherboard?

I did a little testing using the GTA4 benchmark tool. 800x600, everything on medium, no AA, 8x AF, I got 17FPS. I increase the resolution to 1280x1024, everything on high, 4xAA, 16XAF, and I get 15FPS. So, clearly my CPU is the bottleneck, and not my graphics card, right? I'll probably end up getting an E8400. My motherboard will supposedly support a higher FSB if I download a bios update.

http://www.newegg.com/Product/ ... aspx?Item=N82E16819115037

E8400 is a very smart choice, im going for it too i think. I was thinking of E8600 myself but its pointless as you watch the price of the E8400 and E8600. With aftermarket cooler as is 'Arctic Freezer 7 PRO' you could clock E8400 from 3.0Ghz to 4.0Ghz easily without getting any 'hard' temperature problems.

I am still considering buying that CPU. I noticed that my motherboard requires a bios update to support the E8400, though. So just now I flashed my bios. I was able to actually run my memory at 800MHz DDR, and my FSB at 1200MHz. Interesting.