Core i7 Bloomfield Overclocking

[MyLeftNut]

What are everyone's experiences with Core i7 overclocks on X58 platform with 21x multipliers. Does it require less vcore and vtt to reach the same ghz than with 20x multiplier? Is there more stability with lower voltage requirements? Are you able to gain stable high overclocks using 21x which would otherwise be unstable with 20x?

 

[Shmee]

I would say this certainly seemed the case with my C0. Also, it was more stable with an odd multi, so 19x was often more stable than 20x. With bloomsfields, 21x is quite desireable because it allows you to use lower BCLK, meaning less stress on the uncore, board, and memory.

I use my 920 D0 @ 4.2 with the turbo locked, making a 21x200. So far it has been rock stable with my settings, and if I had a better D0 chip, I could go farther. So unless you really want higher memory and uncore frequency, I would recommend using a locked 21x multi, and look into boards that do not have turbo throttling; make sure it really is like an extra 1x multi.

 

[MyLeftNut]

Well, the thing is, I'm pretty sure I got a good chip that can go much higher, I've seen others with my batch at 4.5ghz. I'm at 4.4ghz with HT off right now and it seems with the current P6T WS Pro board I'm using with 20x multiplier, I'm using quite high VTT (1.38) with it cuz I'm doing 20x220. I have the chance to get a UD5 as well, perhaps with the 21x multiplier, I can do with lower VTT and have 4.4ghz HT on.

 

[Shmee]

perhaps, or go for higher (220x21) But yes, I hear that the UD5 should have better BCLK support than the asus board, not positive though. If I were you, I would wait for the next gen UD5 type board, possibly with a hydra 200 chip. No point getting a current board right now IMO until the hydra is out, especially since you already got a decent board and a great OC.

I am curious, what vcore do you have and what load temps for 4.4?

 

[Ben90]

Basically whats been said; it gives a little bit more flexibility i.e:
If you know your ram is stable up to 852mhz
your bclock stable up to 224
and your cpu stable up to 4450 mhz

I would run bclock 212 at a 21 multi because your ram would be running at 848mhz and processor 4452mhz vs if you were stuck with a 20 multi:
I would run a 222 bclock; but have to drop the ram multiplier from 4 to 3 because your pushing the ram too hard for final clocks of 4440mhz/666

Lol i made those max clocks up completely random before i started the math of what would be best; and it worked out pretty perfectly to show the flexibility of a 21x multi; Other scenarios though; a 21x multi might not be the best case as im running 19x right now

 

[MyLeftNut]

I think with 4.4ghz 20x220 I was using something like 1.32 vcore (load). All of these volts were with LLC turned off cuz if I turned it on for some reason it would throttle pretty much regardless of voltage. Using 21x210 for 4.41ghz HT off I needed around 1.27 vcore and around 1.275 for vtt but I think that's the limit until throttling kicks in a drops me back to 20x multi. Right now I settled for 4.2ghz HT on at 1.19 vcore and 1.25 vtt using 21x200. A huge difference compared to using 20x multi where I had to have like 1.24 vcore and like 1.3 vtt. The real problem is this damn throttling that gets in the way of this overclock. Once I pass a certain voltage point the throttling creeps in so I really don't have much room to move up.

Load temps for 4.4ghz HT Off was 71 C with TRUE Black REV C

 

[Shmee]

cool, lucky you got a good chip that takes low voltage. Seems like you will be needing a better board to max the OC. A UD5, or the next gen UD5, should serve you well. Also, have you tried a bios update to get rid of the throttling?

 

[MyLeftNut]

Unfortunately, Asus did not release any of those modified test bioses for the P6T WS Pro. They did release one for the P6T Deluxe and P6T6 WS Revolution. My board looks very similar to the P6T6 WS Revolution and I'm not sure if I can crossflash to that bios. The differences are the P6T6 has like 5 PCI-E 16X/8X slots as the only expansion slots, whereas, mine has 2 PCI-E 16X, 1 PCI-E 1X, 2 PCI-X, and 1 PCI slot. The rest of the board is like 95% identical in appearance.

 

[imported_Shaq]

I have seen this before. 19x + turbo needed less voltage than doing 20x. Kinda strange.

 

[MyLeftNut]

Well, I've heard 2 different theories for this. One being that at 20x the frequencies are too similar to many other onboard frequencies, hence clockrates are hindered by crossstalk. Another being that with the 20x multiplier, the QPI reaches the 4ghz limit too easily and causes instability. Therefore, the need for higher voltages to stabilize the clocks. I personally find that to generally be true. I can run high bclks, but things get unstable if QPI or Uncore is too high. If only Asus could just rid their entire P6T lineup of throttling on their next bios update.

 

[Shmee]

that would be a nice update, wouldn't it? Also, while I dont necessarily recomend it, you may want to search on the possibility of crossflashing to see if it is "safe."

I did it many times with my old 680i LT, but there were documented results (read forum posts) of people getting better quad overclocks with cross flashing. Just make sure that you arent the first one doing it, and that noone has had serious issues trying it, which is my advice when doing something like this for most people, especially if they dont have the money/dont want to replace it.