Poor i7 Overclocking - Motherboard problem?

[aznxk3vi17]

Despite people claiming a 50% overclock on every single 920 out there, I cannot even seem to get mine stable at 3.8 GHz. Right now, my BIOS settings look like this:

CPU mult: 19x
Bclk: 200
QPI: 18x
Uncore: 3200 MHz
Vcore: 1.35
QPI/DRAM: 1.35
DRAM: 1.64

This gets me 3.8 GHz while maintaining the default rated speeds for my current RAM (the G.SKILL at 8-8-8-21 @ 1.6-1.65). However, Prime95 just doesn't like it. After usually 30 minutes to an hour, I get a hard freeze. My temps are around 70-80 load, which are high, yes, but definitely manageable temperatures, especially compared to some people have been getting (I have seen temps as high as 97).

Then, I thought about it differently. I had just gone in gung ho putting in numbers, instead of finding individual limits. I put the CPU multiplier down to 12x, and set off to finding my max Bclk. Apparently, my motherboard cannot sustain a Bclk of more than 205, regardless of the CPU multiplier, so I've ruled out my CPU. I don't really want to put more than 1.35 volts into the Uncore, but my past questions on safe voltages posted here were left unanswered.

That being said, even if I bump the Bclk down and put the CPU multiplier back at 20x, I get the same freeze after about half an hour. It almost seems as if my Bclk has a very low upper limit.

Is there something wrong with my motherboard? Did I just get super unlucky with batches? Or, is it actually my CPU and not the motherboard?

 

[Martimus]

A hard freeze in Prime 95 is usually the RAM. Try loosening the timings.

 

[aznxk3vi17]

Interesting. However, I've seen a trend in the i7 (and confirmed by several posts around the web) that an unstable overclock, whether it be the RAM or CPU, results in a hard freeze in Prime95. Also, my RAM is rated by default to be 1600 MHz at 8-8-8-21. Unfortunately, I have no idea whether it's 1N or 2N. I've assumed 1N, since it manages to boot just fine.

I'll try 9-9-9-24 tonight.

 

[tim924]

Weird,I got mine stable at 3.8Ghz with 1.27V Vcore,try to up your QPI to 1.35 V

 

[ajaidevsingh]

With a P6T Delx and a ULTRA 120 the best clock we could do was 3.6 Ghz "24/7 system". At 3.8 Ghz Prime95 freezes and gives a BSOD in a 24 hr run and even tough the temps are around 86-90C when this happens.

But at 3.6 Ghz the thing runs like a dream low 80's and rock solid stability!!!!

 

[aznxk3vi17]

Originally posted by: tim924
Weird,I got mine stable at 3.8Ghz with 1.27V Vcore,try to up your QPI to 1.35 V

My QPI has been at 1.35 the entire time, and I am unwilling to push it much higher, due to not knowing safe voltages on this chip.

Also, going back to RAM timings, last night I tried decreasing my memory speed from the 8x multiplier to the 6x multiplier. With Bclk at 200, my RAM was at 1200 MHz @ 8-8-8-21. I think with a rated speed of 1600 MHz at the same timings, that the RAM wouldn't be the problem. Am I mistaken on this?

 

[rge]

My i940, have about 20 prime runs and some linx, not a single time did I get an error on prime, 70% reboots, 30% freezes if unstable.

You may just need more vcore or you may be reaching limit of prime stable bclk. Do you have LLC enabled? (Not just that I cant stand intel babysitting of having bios setting = max overshoot, and rather have bios set=idle=load, and then just tell me the overshoot percent/formula and I can figure out where my overshoot max is myself....but with the more load = more vdroop = more instability from lack of enough volts...I think without LLC is a defective mobo design for core i7's, imo.

Using 19x like you are doing is one way of getting higher mhz with lower vcore. The other way is enabling turbo on GB bios, which on i920 gives 21 multi permanently (TDP limit is disabled) not sure if way of doing that on P6. On other hand, if you are reaching your max bclk (for priming which may be different than bootable max bclk which limit 19 multi mhz), and if you cant get 21x191 via perma turbo, you may wish to try 20x200...but that will be with even higher vcore, if yours is like most others.

 

[aznxk3vi17]

Originally posted by: rge
My i940, have about 20 prime runs and some linx, not a single time did I get an error on prime, 70% reboots, 30% freezes if unstable.

You may just need more vcore or you may be reaching limit of prime stable bclk. Do you have LLC enabled? (Not just that I cant stand intel babysitting of having bios setting = max overshoot, and rather have bios set=idle=load, and then just tell me the overshoot percent/formula and I can figure out where my overshoot max is myself....but with the more load = more vdroop = more instability from lack of enough volts...I think without LLC is a defective mobo design for core i7's, imo.

Using 19x like you are doing is one way of getting higher mhz with lower vcore. The other way is enabling turbo on GB bios, which on i920 gives 21 multi permanently (TDP limit is disabled) not sure if way of doing that on P6. On other hand, if you are reaching your max bclk (for priming which may be different than bootable max bclk which limit 19 multi mhz), and if you cant get 21x191 via perma turbo, you may wish to try 20x200...but that will be with even higher vcore, if yours is like most others.

I'm on the ASUS board, and I have no Turbo option. Also, I do have LLC enabled, but I've observed the voltages closely in CPU-Z, and they are hitting their expected values.

All in all, I'm hesitant to push voltages too far, because nobody has yet clearly pointed out safe limits. I'm keeping my Vcore <=1.35, and the QPI/DRAM voltage <=1.35 as well, until somebody tells me otherwise that it's safe to push them higher for 24/7 stability. I just don't want to degrade the lifespan of my processor noticeably.

 

[rge]

Gotcha and probably smart until we learn more...I am staying within VID range myself, at max VID value of 1.375vcore (though with LLC enabled), and my QPI/VTT is 1.32 (guess P6 calls it QPI/DRAM), and DRAM volts 1.64. Couple others volts at one notch higher than stock, rest stock. I primed at 4.2, but need 1.42 in bios with LLC...so sticking to 4.1 for 24/7 for same reason as you, at least for a while.