I am relatively new to overclocking. I have only OCed my C2D e6600 to 3ghz in the past. Now Ive got the following system:
i7 950 DO revision
Geil value plus RAM 2x4GB (1.6V max 9-9-9-28 factory settings, not timings in my BIOS)
Noctua NH-D14 cooler
GTX 470 Msi twin frozr (I dont think this matters but I just mention it)
XFX 750w pro series PSU
After research and reading, I have found the following settings to give a stable OC of 3.8ghz with high temps though. I did a P95 blend test and it reached 76-78C when it was doing FFT 8k or something, but at times it was floating at 68-72C. Here are the settings for my 3.8ghz OC:
I have tried different versions of 4Ghz as well, i.e. 21x191, 19x211 and 23x 174. However, I managed to get a stable OC with three notches higher voltage than my 3.8ghz: around 1.32 in BIOS, a bit less in cpu-z. I had to set lower Ram voltage in all these to get a more stable OC. I am not sure though this affected the OC as I was changing other factors at the same time as well, such as QPI etc. For my 4Ghz OC I used higher QPI: around 1.3v. Generally, my temps @ a stable 4ghz were high, above 82C. I only let it test for 1hour, as I didnt want to keep it running in that high temps.
is there anything wrong with my Noctua? I have tried reseating 4 times using different techniques: less paste (arctic silver 5), more paste, and tinting the heatsink/line on the CPU. The transition from less to more thermal paste seemed to have made a 4-5 degrees C difference in my temps. The noctua's surface is not smooth but with some wavy lines while the cpu is smooth of course.
The air circulation of my case is like a freaking vortex; only a vacuum cleaner can create better circulation . Ambient temps are quite high, especially today that it was 20C in UK and even higher in my room (I still have the heating on; I am crazy I know)
Another thing is that there is a significant temp difference between my 4 cores: 3 of them are running with 1-2 degrees difference while one of them is always 5-6 degrees lower than the other 3.
I would really like to achice a stable 4Ghz but I dont know how to proceed; is my RAM not suitable, my cooler, the CPU itself or maybe the mobo??
You may not be able to reach 4GHz. Not all CPUs are the same, some will make it to 4GHz just fine without issues, while others require heaps of voltage and even then may not make it. Overall 70-80C at load isn't horrible for a i7-950, but 80+C at load over a long time period is pushing it, though. Overall your processor just may not have what it takes to get to 4GHz. Your cooler is plenty capable, and you said yourself that the case has plenty of airflow, so both of those aren't a problem.
I would actually recommend dropping your CPU frequency slightly to something like 3.6GHz, lower the voltage accordingly, and then re-enable SpeedStep. I say that because I prefer longevity over raw performance when I overclock, and I don't like the having CPU running at full speed non-stop no matter what the load, wearing out more quickly, rather than throttling down and reducing heat and wear. If you really want to go to 4GHz you'll just have to deal with the heat, because I can't think of anything to reduce your temps, especially given that you already have a good cooler and good airflow.
As far as the temperature delta between different cores is concerned, I would not be concerned about that. Some cores just run hotter/cooler than others naturally, sometimes the temp sensors give slightly different readings, or maybe the cooler is removing heat just slightly more quickly/slowly from some areas of the chip package.
I actually experimented a bit and found a good combination of settings which let me have a stable 3.8ghz OC with relatively low voltage (1.24 in BIOS) with good temps. I have though a question:
I can P95 infinitely without errors with small FFT's but with a blend test I am getting an error after about 4 hours. I noticed it gave the error while doing a 1344K FFT. Does this mean that my RAM is not up to the task? If yes, what can I try to fix it?
Will post my settings later, but generally, I set many of them to 'Auto'
You can still run a dual channel setup with X58, you just won't get the best performance. To fix RAM instability you can decrease speeds, loosen the timings, increase voltages, or some combination thereof. Obviously the best choice depends on your current settings. I would advise, however, that you run Memtest first before you start adjusting your RAM settings to verify that there is a RAM problem causing the failure.