Voltage question on i7 950

[Steppen_Wolf]

Hello, there first time post!

I'm learning a lot about overclocking and just got a new Cooler Master hyper 212 CPU cooler to do some moderate overclocking. My question is that I am able to run a solid overclock at 3.8GHz with a 24 multiplier and 160 Bclock on 1.3v. I have to add almost a tenth of a volt at 1.38v to get my CPU stable at 4GHz which my modest cooler cannot cool well enough as my temps jump up about 20c. My specs:

i7 950 3.8GHz
Asus Rampage iii Gene
900w Rocketfish PSU (I know, I know, reviews are decent though)
300GB Western Digital 7200RPM HDD
6GB Corsair DDR3 1600MHz
2 x Evga GTX 660 ti 2GB sli
Windows 7 Ultimate

Like I said I'm still learning. I have my QPI/DRAM set to 1.4v which doesn't seem to hurt my IOC temps. I tried with v-droop protection both enabled and disabled with no noticeable improvement in stability at a lower voltage. I have left everything else at "auto". Is 1.38v what I should expect to run stably at 4GHz and should I just accept that my inexpensive cooler just can't get the job done or are there something else I can look at?

Any help would be much appreciated, all I know is what I've learned in the past week of trying to figure this out! 'Preciate!

 

[djscrew]

My chip will run at a much lower vcore then yours at 4 ghz, but every chip is different.

4 ghz is a solid overclock for our chips but that is also a hefty voltage to pump through it.

Actually, looking at your post I have spotted a big problem. You are using the 24 multiplier. That is a terrible multiplier to use and is known to be unstable. You want to run odd multipliers, 191 x 21 should do the trick nicely. You might have to increase IOH voltage a bit to 1.15 or so, and QPI should be fine at 1.4.

Try your settings at 191 x 21 and if its stable bump the vcore down to 1.30 then try 1.25.

make sure LLC/vdroop control is enabled.

Have you disabled all the items stated in the overclocking guides, such as c-states, spread spectrum, etc?

 

[Steppen_Wolf]

Have you disabled all the items stated in the overclocking guides, such as c-states, spread spectrum, etc?

Thanks for the reply, I know I have c-state disabled but I'm not sure about spread spectrum. I have followed this oft sited guide pretty closely. I will try what you suggested with the IOH voltage and multiplier and post back.

 

[Steppen_Wolf]

Yeah, still getting blue screen. Made sure v-droop control was enabled, bumped my IOC voltage up to 1.2v just for kicks, turned off spread spectrum and set my clocks but Windows wouldn't even load. Tried 1.33v and that let me boot but I got a blue screen when loading a game. It is more stable though. Most people are saying not to bother with the CPU/IOC clock skew on more modest overclocks, is this true? Also I have turbo boost on which I'll disable. I'm not sure where else to take this.

 

[djscrew]

Did you correct the multipliers?

 

[Steppen_Wolf]

I did! I'm having success now. I set the multipliers like you suggested. My v-core is sitting at 1.33v which is as low as I can get and keep it stable. I had to raise my IOC voltage to 1.2, any less and I'm crashing (I haven't tried every thousandths of a volt variation). My IOC temps are a big high but manageable and my CPU temps are better than they were before at 3.8GHz. I really think raising my IOC voltage and disabling CPU and IOC spread spectrum made this possible. Big big thanks!

BTW, 2.4v on IOC? Too much? My mobo specs say that's within range but it seems high.

 

[redduc900]

There is no IOC voltage. Besides Vcore, VTT, PLL, and DRAM voltage, there's either IOH, IOH PCI-E, ICH, or ICH PCI-E voltage. I assume you're referring to the IOH voltage (MCH / NB voltage)?

 

[djscrew]

2.4 is way high for IOH voltage

~2.0 would be acceptable but should be necessary since you're not running that much RAM, unless you have 6 x 1 GB sticks which I find unlikely. Regardless, the Northbridge shouldn't need that much voltage on your setup.

Actually I don't know of a single voltage that would be in the 2.4 range.

 

[Steppen_Wolf]

Sorry a couple typos, it was late. I set the IOH voltage to ~1.23v. I really can't keep it lower as I get a BSOD eventually. I still wish my v-core was lower than 1.33v because some games are pushing the CPU temp a little too high. I get BSOD at 1.3v. The thing is I'm able to run games for hours no problem but prime95 shuts me down almost instantly. I'm beginning to suspect my PSU is my problem. I just don't have the money to spend another $150 bucks on a better one.

I have a QPI speed option, is it worth bumping up? My IOH temps are pretty high and I don't want to push it unless there is a significant performance increase. Right now my CPU is bottlenecking my GPUs pretty noticeably on benchmarks and I haven't done anything with my memory (it's at ~1550MHz) or QPI.

 

[rainman33]

As you see in my SIG I have a similar setup as you. Although I water cool, I have some settings for 4 GHz that you MAY be fine with since it is at a lower cpu voltage. Now my chip may also be more stable at a lower cpu voltage than yours but hey, give it a shot.

First go into the BIOS and in CPU configuration disable C1E, TM, and speedstep.
scroll down to "extreme OV" and enable it.
Go to "cpu load line calibration" and enable it. It improves vdroop directly
Than scroll down and disable cpu spread spectrum and PCIE spread spectrum.

BCLK - 191
MULTI - 21
cpu voltage - 1.32
cpu pll - 1.86
qpi - 1.35
IOH - 1.2
Dram bus voltage - 1.6

Now keep in mind all chips are different as previously stated in this thread, but 1.32 for your cpu voltage should be close to what you need. You may have to bump it up a tad, not too much while keeping an eye on temps but if it boots into windows at that setting than try to lower it until it crashes using prime95 as your stress test program running for an hour or so. As I found out it takes patience and time. Good luck and let us know how you made out.

 

[djscrew]

sry for missing this post

what is your QPI at? I would say bump that up and maybe that would let you lower the IOH 1.23v is really high for your NB

you should be able to go under 1.33 if you have a good chip, each chip is different though

 

[freeagent]

I have to agree, every chip is different, and they each like things done their way Multiplyers are something you would have to play with. My particular cpu loves the x21 and the x24 multis. Specifically to run over 4.2ghz (1.3v) I need to kick over to the x24 multi. For that I drop my bclk from 200 to 184, and kick my uncore up to 3500mhz or so and my mems run at 1844mhz. (4425mhz @ 1.4v, 1.42vtt) I havent had a bloomfied (c0) for a couple of years now, but my guess is you would need around 1.37v on your qpi/vtt. I could be wrong tho

 

[rainman33]

@ stock speeds his IOH should be at 1.17 - 1.18. +.02 to +.03 of a volt should still be well within safe temp range. djscrew is right. Bump up your QPI but do not exceed 1.4v. Anything above 1.4v for general use will be too high and can cause problems. What are your NB temps @ 1.2v anyway?

 

[freeagent]

My previous cpu was a 970 Gulftown, and now I have this Westmere, I have had no problems running 1.425 qpi. I dont know about youre board, but with mine 1.425 after droop is 1.39-1.4, on a bloomfield that should be no problem, even 1.45 should be ok.. tho probably numbers you arent used to seeing, possibly because you only have 4 cores, or slow ram, or both. As for IOH I am ok with 1.27v-1.325v.