Hi there!
I have decided to throw the towel in my £37 pound PGA478 build and am going for an i5 2500k build for under 160 pounds. I have already read that it is impossible to overclock on Q77 chipset, only by BCLK but you know that is pretty useless - extra few Mhz here and there...
I would like to know whether it may be possible to use throttlestop to overclock and overvolt the CPU. I am aware that Z77, Z75, P67 (and more) chipsets can overclock through BIOS but doesn't throttlestop write multiplier instructions directly to cpu so bios support is not required??

I am quite confused by this and you know a decent Q77 board is a good 30-40 pounds cheaper than their overclocking variants so it saves money and allows me to get better parts. I may not be able to hit 4.5 because of no VRM cooling but anything above 4ghz is a BIG jump from my core 2 duo t5800!!!
If there is like V-Core limit in BIOS it would surely be possible to mod bios to erase the limit?

Thanks for your help!

I can't comment on throttlestop, maybe someone else knows more about that.

If you want to play with modifying BIOS, even on Q77 which will be limited, do not get an Intel branded Q77 board, BIOS modifying is limited and reflashing modified BIOS requires flash programmer and jumper cable.
I doubt you can do 4Ghz on Q77, look maybe at P67 or Z68 boards instead. For that CPU and overclocking, P67/Z68 will be cheaper than Z77 and you can overclock without hassles, and mod BIOS too easier if you want.

Hi Lost_N_BIOS, good to see you again!
Ah. I was planning to get an intel branded board. Looks like I will need to go elsewhere then.
Apparently P67 will not allow me to overclock GPU? Or is that the iGPU (in which case it doesn't matter as I'm getting a GPU too.)

Hey!! I thought your name looked familiar too and had to go check

You can get Intel board if you want, I was only suggesting maybe better series since you want to overclock. That and Intel BIOS cannot be modified as much, nor as easily as the other brands.

Yes, you can overclock iGPU on P67, at least I think on most boards, but onboard graphics is not something you want to overclock anyway, it's for basic use like browsing the internet, not really for gaming or anything where you'd want to overclock it.
P67 you can overclock the CPU for sure, same for Z68 but Z68 might be as expensive as Z77 board still. P67 should be cheap though, most sold to upgrade to Z68/Z77 so P67 usually cheap price always
Plus the B2/B3 stuff brought that series down too. Be sure to get B3, most are all that anyway so you usually don't have to verify