you need something like this


available at sri computers, or you may DIY yourself, since the fan is only one positive and one negative

//moved to Q&A

Everything has a limit of its capability. That's the limitation of your CPU or RAM or motherboard. Tweak some settings if you can, otherwise you shall accept that the best clock is 3.75GHz.

The fundamentals of overclocking. If the core frequency is too high, you need to compensate the core voltage. As FSB increase, your RAM may not be fast enough, you compensate voltage or loosen timing or change FSB:DRAM ratio. If you have done all to compensate the instability and if it doesn't work, it's just going to be like that. There are reason why Pentium II are 350MHz in the past and not 3.75GHz.

it wont help if u dont understand the basic of overclocking.

E8400 @ 4ghz @ 450 x 9 u can run the ram at 900mhz and most 800mhz value ram can do that.

pump up more vdimm.

not really. there are walls in overclocking.

correct me if i'm wrong, but processor won't be running if it didn't received enough juice, aite?

increase in frequencies need to be compensated with extra voltage. not enough voltage - proc not powered up - fan stopped.

TS.
I'm still waiting for your answer. and also what's your PSU brand/model?

@mengsuan
I knew that. I was not asking TS about fundamental of overclocking / overclocking limitation.   

then there's wall made of vdimm

then there's wall made of motherboard chipset.