i5 2500k overclocking turbo mode

[amenx]

My bro bought an i5 2500k and P67a-UD4-B3 board based on my recommendations. He doesnt care much about OC'ing but I told to go for a good OC board as it gives him the option down the road to extract more performance vs needing to upgrade sooner.

I noticed in the boards options, aside from the base multi, that theres a turbo multi for each core, ie, 37, 36, 35, 34.

I know its easy to OC the chip from the standard multi, but the idea I have in mind is to keep the base multi low or at default (33-35) and just increase the turbo multis. The logic behind this is that over 95% of the time he wont need the extra power/heat, so it will be idling in low clocks with speed step (1600-2000mhz) rather than 4000mhz all the time. But if he needs the power, turbo mode kicks in. So is it possible to OC just the turbo modes?

Thanks.

 

[Crap Daddy]

That's the only way it works on SB except is you disable all the C states and EIST speedstep. Just change the multi (or CPU core ratio something) to the desired number and you're set. Until 4.3-4.4 it should work with everything else on auto. Hope you have an aftermarket cooler since you'll need it under heavy load at OCed turbo.

 

[amenx]

Yes but can I just OC the turbo multis rather than the main multi? You see I'm looking at turbo mode to go up to 4-4.5ghz when needed but for the main clock to be default (3.3ghz). Of course I want to retain C states and Eist and vcore at auto so it will dip low (-1.0v) and 1600-2000mhz when idle. Cooler is Noctua DH-12 I think.

 

[blackened23]

Yes but can I just OC the turbo multis rather than the main multi? You see I'm looking at turbo mode to go up to 4-4.5ghz when needed but for the main clock to be default (3.3ghz). Of course I want to retain C states and Eist and vcore at auto so it will dip low (-1.0v) and 1600-2000mhz when idle. Cooler is Noctua DH-12 I think.
.

Yes, it is possible. By default-- unless you specify otherwise it will be clocked at 1600mhz for low load tasks, and kicks into turbo at 3.3+ GHz by for turbo mode. Like someone else mentioned you have to enable EIST and C states in the BIOS (should be by default)

Yes, you can change the multiplier for either the EIST state (1600mhz by default) or the turbo state (3.3 by default) in your BIOS. Obviously no overclock is guaranteed so be sure you're getting good components that will increase the likelihood of your turbo overclock.

 

[Crap Daddy]

bus speed is not to be touched in SB, it's called base clock or BCLK and it's pretty much fixed at 100Mhz, or it can be at your own risk at a max of 104-105. But it's uselles since you have an unlocked multiplier CPU so you mess only with the multi. That cpu ratio is the main multi and it will kick in only in turbo. Check and see that at idle you have 1600 and then under load it goes up to whatever you fix it to be. In fact I never see the default 3.3 on my system, it's either 1600 or up to different turbo speeds.

 

[amenx]

Sorry I wasnt referring to the 100mhz base clock, I know not to mess with that. I was referring to the individual core multis vs the CPU default multi which is 33. I want to keep the default main multi as is or low (at 33-35) but raise the individual core multis (defaults are 37, 36, 35, 34) to perhaps 42, 41, 40, 39. So that the CPU runs at normal power saving mode when idle (1600mhz) but have high turbo performance (up to 4200). Sorry if I wasnt clear earlier.

 

[Crap Daddy]

I understand and that's what I've been saying. If you just up the multi, don't know what is the exact setting in your bios, it will do just as you said, it will run at power saving mode 1600 idle and turbo to newly set clocks. Now the default is 3.3, if it's one core under load then it's only that up to 3.7, you will probably never see that, for 2 cores there's 3.6 (on 2 cores the other ones are at idle 1600) if it's 3 cores needed then you have 3.5 and one idle and when all four are under load, as in BFBC2 game you'll have 3.4 on all. I'm not sure if you can set different turbo multis on different cores but if you just fix manually your multi at 42, it should work on all other settings default including vcore then you'll have that value as a maximum when under load. Try to run prime or any something like cinebench or do a handbrake encode and monitor your speeds with CPUz.

 

[MrTransistorm]

The usual method is to set all four turbo multipliers to the same value while leaving the base multiplier at stock. That way it will jump up to that frequency when needed no matter how many threads cause it to get there.