Core i5 2500k paired with Corsair Hydro H100

Was curious if overclocking I would notice any difference in performance at all I followed a video on youtube and got to 4.5 ghz really easily with temps in the 30's. I put in Cougar fans in replacement of the stock corsair fans in a push config. Below is my setup just curious if I overclock if I'll notice anything. And what temps should I expect.

Intel Core i5 2500k
ASRock Z68 EXTREME4 GEN3 LGA 1155 Intel Z68
Corsair 2x4 GB's DDR3 1600
Corsair TX650W Power Supply
Corsair Hydro H100 (pre-filled water cooling)
OCZ Vertex 2 SSD 90 GB Boot Drive+Game Drive
Seagate Barracuda 500 GB Sata II HDD
ATi Radeon 5770
Creative Sound Blaster X-Fi Titanium Fatal1ty Professional Sound Card
Coolermaster Sniper Case
LG HD-DVD/Blu-Ray player


It depends what you stress your rig with. If you are OC'ing for games it depends on whether the games are CPU or GPU intensive. You are likely to see higher temps on the CPU with something like Flight Simulator than with Crysis II, BF3, etc.

You should be concerned with temps exceeding 60 C for a prolonged period. Really critical heat starts 80 C.

Running Prime 95 will probably get you above 70 C. It is not cause for concern as Prime 95 is an artifical stress test and does not indicate normal operation.
Honestly I only play games like WoW, and Starcraft. I would like to pick up a shooter at some point but at the time being the only demanding game I play is Arkham city. and yes idles around 38 and load around 58 prime 95 I ran on stock and it was around 58 but i ran it overnight under heavy load.