new build

Hello everyone,
I'm not sure if anyone remembers me, but I was having trouble deciding on some things a month or two ago and you guys helped me decided.

Alright, I've finally completed my build, and I wanted to post the results since I sought help here. Now, this build isn't confirmed 100% stable yet but it has been running for about 2 hours stable with no errors in Prime95.

There are some curious things maybe someone here could explain.

My build is comprised of:
CPU: i7 950
GPU: Gigabyte 460 x2 (SLI)
PSU: Antec Truepower New 750W
Mobo: ASUS Sabertooth x58
RAM: OCZ Gold series 1600 6gb 8-8-8-24-1T
CPU Cooling: Prolimatech Megahalems Rev. b
Case: HAF 932
Heatsink fans: Cooler Master Blademaster 120mm x 2 (push-pull) running about 70%

Alright, so here are my stats currently. Keep in mind I was never going for a super-high clock.

CPU: running at 4.1 GHz, 205 bclk x 20 multi
RAM: 8-8-8-24-1T running at 1638 MHz (2:8)

CPU voltage is at 3.92 V. RAM voltage at 1.65 V. QPI/DRAM voltage at 1.5V. QPI link is on Auto. Uncore is about 2.5x DRAM freq.

My CPU temp is at 83 max under full load (Prime95 + this browser). Core 3 and 4 are at 79 max. I know that's a tad high, but I'm not really worried because I haven't exhausted my options. I think I have too many fans as intake, but I've been too lazy to actually check thus far. I've just left the case fans as they are default on the HAF 932.

The interesting thing (again, not desperate for more power) is that 4.1 GHz is the absolute highest I can get stable. 4.2 GHz (210 x 20) will boot Windows but freezes when I try to subject it to Prime 95 after a couple of minutes. 4.3 GHz (220 x 20) is completely out of the question. I think my Sabertooth is hitting the wall here with that 220 bclk. It gives a bluescreen that says "A clock interrupt was not received from a secondary processor". I tried this repeatedly with that results after probably less than a minute each time. I also tried lowering the multi and upping the bclk and could barely hit 4 GHz.

What do you guys think? I can tell you that the temp difference between 4.2 GHz and 4.3 GHz is minimal.

Btw, I have tried this with the Vdroop enabled and disabled.

if you turn off Turbo and hyperthreading you will gain up to 10degrees in your favor..

also, cpu voltage at 3.92??? your chip should auto-shutdown cause of the heat that much power would throw at it... cpu voltage, for safety sake without going LN2 cold etc should never go over 1.35 give or take.. so guessing thats not the cpu volts.

also try using odd multipliers (211*19 for 4ghz, 226 or 227*19 for 4.3) sometimes these i7s like odd multipliers to get higher clocks..

imo if you're not benching your system you should stay at 4.0Ghz and keep the temps as low as possible.. the real-world difference between that and 4.2 will not be very noticeable to your eyes than it would be to benchmarking software.

As for your fans.. the default 932 setup is what they consider pretty optimal, but you can almost always do better. IMO front/side/bottom of case should pull air in, top/back should pull air out. The HSF fans should point from front of case to back of case and not from bottom of case to top.. positive pressure in this case is tough to do since there is a ton of open mesh, so you're always moving air out even if you aren't pulling it out with the top/back

Also remember to turn off the C1E and speedstep stuff too at first and add them back in if you can keep it stable!

Oops! Sorry, I meant 1.392 V for the CPU voltage. Nearly 4 would be a little much
Hmm, seems I'm still getting BSOD, but the code is odd. I looked it up and it seems like it may be a driver interacting badly with Windows 7 under very heavy load instead of my OC not being stable. I'll look into it. I've been getting the same code several times, and just been upping the voltage.

SYSTEM_SERVICE_EXCEPTION 0x3B

I'm downloading things now to look at the .dmp file. I was getting worried because I've upped the voltage by like 5 steps (still not up to that old figure of 1.392 yet, as that was higher for the 4.3 GHz clock) with little or no improvement in stability (unless of course it's Windows 7's fault and not my clock). Maybe I'll try just running Prime95 at stock speed and seeing if I get an error.

usually that is recommended... if your system doesn't pass p95@ stock you gotta figure out what hardware is messed up

Alright, it appears I've stabilized the OC with one more increment of voltage (I lowered it significantly and crept back up) to 1.368 V. It ran 7 hours of Prime95 with me still using it for the net and streaming video before subcoming to a BSOD (SYSTEM_SERVICE_ERROR 0x3B).

I just have an intuition that this is not the CPU OC causing this problem. I believe it's either the RAM crapping out (I may raise the QPI/DRAM voltage a touch), or a driver conflict. I feel as though that voltage should be plenty for a 4.1 GHz clock. My temps peaked at 85 on Core 0 during those 7 hours, though it spent most of the time I checked on it at 81.

ASUS's PC Probe gives me a warning color on the NB temps (71 degrees from the heatsink fans blowing on it). I also OC'ed the video cards so that GPU 1 (the one sandwiched between my sound card and the other GPU) maxes at 98 degrees in Furmark. I may lower the GPU OC just a bit, I haven't decided yet.

I'm going to run Memtest overnight to rule out the RAM, though honestly if the RAM is the problem I'm not sure what I'm going to do about it short of lowering the multi from 2:8 to 2:6, which would be a huge hit to the frequency... My bclk isn't stable at 220, so I either have to sac CPU freq or RAM freq if my RAM is to blame. Either that or spring for 2000 MHz rated RAM, but honestly I've spent all the money I really can.

Update

UPDATE:

Alright everybody, I dropped the CPU voltage back to 1.36 V and also changed my frequency configuration (195 bclk x 21 multi), resulting in a completely stable 4.1 GHz clock with 1583 MHz memory.

It ran 12 hours of Memtest86+, 12 hours of Prime95, and 50 passes of Intel Burn Test.

I'm thinking either my processor didn't like the bclk range I had, or my motherboard is just a little weak in that department (I suspect the latter). But thanks everybody for the help!!

~firelord84