I have a Pentium D 930 and have it currently overclocked to 3.3Ghz at something around 2.9V. I'm able to get the CPU up to 3.5Ghz max and have it be stable at this voltage level, but if I increase the voltage any more my computer doesn't even post. As of right now I have stock cooling on it, I may be wrong, and probably am, but I don't know if getting a better heatsink would allow me to overclock any more than I already can, so should I just let it be and consider myself lucky that I can OC it that much on stock or is there something else I could do that may allow me to further increase the speed without having a firework show inside my case?
It depends on what you use your computer for. You should stop at 3.3 with stock cooling if you use your computer purposes other than games. The other question to ask is what is the performance difference between 3.5 and 3.3 for the applications you commonly use?
As of lately I've been doing huge amount of multi tasking that usually tax my CPU. So the way I'm seeing it right now is, the more power I can get out of it the better off I am. And the only reason it's a 3.3 right now is because my room mates keep my place a little on the warm side, so I'm just allowing it to breathe better.
You just have to make sure that your CPU is the limiting factor. How much memory do you have? Also, when you are multi-tasking, does the CPU utilization hit 100%? One more question, assuming you are hitting 100%, what are your temps?
Just a straight guess, but it sounds like additional cooling won't make a difference.
1.29V is a lot better. If your temperatures under load are not high when you are at 3.5GHz with 1.29V, then getting better cooling will not help your overclock at all. (If it is your CPU that is limiting you.)
Check what the speed that RAM is running at. When at 3.5GHz, I have your FSB speed at 233MHz, and your RAM at 933MHz (assuming a 1:1 FSB to RAM ratio). If you are running at 1:1, then the RAM may be holding you back because it is only meant for 800MHz.
Let us know your RAM speed, and the FSB:RAM ratio. You can get these values from CPU-Z.
Getting a better heatsink would allow a higher max OC, but that is because it will allow more voltage increase because it can handle the heat. anything under ~1.425 is fine if the temps are ok. You should be able to hit 4ghz fairly easily with that CPU with a good aftermarket heatsink.