Question about CPU Coolers

No, a new cooler would only help with temps, you are having stability problems which is likely more indicative of too low voltage or a need for RAM tweaking. What voltage is your CPU running at now, what are your temps, and what are the specs on that RAM?

The P5Q is fine. You have hit a wall in which the stock voltage will no longer do. You must manually set the voltage.

Keep the voltage under v1.45 at the very most and keep the temps under 65c and you will be fine.

4 sticks of ram is also part of the problem. 4gb in a 2x2gb configuration puts less load on the mobo. To test this out, see what you can overclock to with just 2 sticks. If it does well enough, a 4gb kit of corsair is currrently $25 after rebate.

An oem vs. stock cooler will help, once you can boot and get the temps up high under load. Look at Xigmatek for a cheap and effective cooler.

At a clock rate of 3.0 or better, the vga card is much more important for gaming than the cpu.
At that level, overclocking is good for bragging, but it will not net you as much increase
in FPS as a better vga card will. Today, very few games can make use of more than two cores.
Flight simulator X and supreme commander are exceptions. It is not a trivial matter to code multi threaded programs,
and game vendors will not sell too many games that require quads to run.
I don't see this changing in the next couple of years.

Net: a faster duo for the increased clock speed.