I've been lurking at Tom's for many years but this is my first post. Anyway, I need help determining overclock settings with my newest system. For about 20 years, I have been servicing and selling computers but have never really done much in the way of over-clocking. Now I know why - it is driving me crazy! I have done much research in the past few weeks and tried numerous suggested setting combinations but I can't seem to get anything stable above 4000Mhz. Okay - my setup: ASUS SABERTOOTH P67 (REV 3.0) LGA 1155 Motherboard / i5-2500K Sandy Bridge 3.3GHz Processor - Mfg. in Costa Rica / ASUS GTX-460 (Fermi) 768MB Graphics Adapter / Patriot Gamer-2 8GB (2 x 4GB) DDR3-1600 Memory / Thermaltake Black Widow 850W CrossFire Certified 80 PLUS BRONZE Certified Active PFC Power Supply / Antec KUHLER H2O 620 CPU Cooler / WD 300GB Velociraptor / Win7 Ultimate. The 'stable' settings I'm using now (for 4000Mhz) are as follows: Load Line Calibration=Auto, CPU Multiplier=40x, VCC=1.3100, PLL=1.9000, Internal PLL over-voltage=Enabled, Phase Control=Optimized, Memory is manually set to DDR-1600 @ 1.65 volts. All other settings are either AUTO or Default. Using these settings, my CPU Temps stay at or below 40C and the BSD's have not appeared. Incidentally, when BSD's do show up, they are usually of the PFN_LIST_CORRUPT type. Also, I have tried using the Auto-AI Overclock Tuner (worthless?) in the BIOS but it BSD's or crashes before login. I don't really want to go to anything extreme but would like to hit 4500Mhz with 100% stability. Any help or suggestions will be greatly appreciated.
Whew! I managed to power through that mega-block of text...
Those auto-overclocks are pretty much fool-proof, and you can't really go wrong with them. If that doesn't work, you likely have a "dud" processor as far as overclocking goes.
Supporting evidence: You can't get above 4.0GHz on 1.31v CPU voltage with PLL Overvoltage enabled. The average 2500K should be able to get closer to 4.4GHz with those settings.
Just out of curiosity: Have you tried skipping a few multipliers? Increase the CPU voltage to 1.35v and try a 44x/45x multiplier. On occasion I have seen where a CPU/mainboard combo just doesn't "like" certain multipliers.
Thanx for the reply. From what I've read about my CPU Batch number, it was mfg'd. in Costa Rica. Most of what I've seen posted about that batch say that VCC doesn't even need to go above 1.256 to get 46x multiplier and stable (48x @ 1.3120 & 50x @ 1.420). In the past three weeks, I've tried at least a coupla hundred combinations with multipliers from 35x to 50x, along with varying PLL, VCCIO, VRM Freqs., Phase Controls from Optimized to Ultra-Fast to Extreme but I just haven't found many sweet spots, except 40x @1.3100v & PLL=1.9v, where I'm stuck at now. It is possible that there is just too much information out there and I'm misinterpreting some of it. Some say the Costa Rica chips are great and some say they're crap. Same story with the ASUS Sabertooth and Patriot memory - some say they're great and some say they're garbage. It's very hard sifting through all the available info to try and figure out what is accurate and what is crap. I may just clear CMOS, go back to scratch and try one thing at a time. I've been keeping a notebook which is now full of pages and pages of settings, suggestions, O/C websites, fails, and successes so at least I know a lot of stuff that doesn't work. I am suspecting that my memory may be at least partly to blame with all the PFN_LIST errors I've had - and I think simply setting it to XMP, which should be a good safe setting, is causing BDS's. I'll pick up a couple of new DDR3 sticks of a different brand just to see if it makes any difference. I can also fool with different CPU's because I am a reseller and have at least two new builds using i5-2500k's coming up in a week or so. Do you have a suggestion as to which batch # of CPU's are the best for o/c'ing - I can request CPU's with specific batch #'s from my distributor - additionally, is there a favorite brand/type/size of DDR3 stick that works best in an o/c.
Thanx again and ANY input from ANYONE reading this is welcome,
Overclocking the average Sandy Bridge K CPU is really easy:
1. Set CPU voltage to 1.3v-1.35v
2. Set CPU multiplier to 45
3. Save and exit.
Without fussing with any other settings, this should work.
You've definitely gone above and beyond the effort needed to overclock higher than 4GHz. I really do think you have a dud overclocker.
I don't keep track of specific batch numbers, but those with a C in them tend to require less voltage for their overclocks. My 2500K (L047B217 Malaysia) requires 1.488v (with occasional spikes to 1.496v) for 4.8GHz. If I set the voltage lower than that, it'll work for most stuff but will reboot itself after 5+ hours of Prime95. Any attempt at higher speed results in BSODs after a random amount of time.
Have you tried different ram? When I was working with a core2quad I had trouble overclocking with 8GB of ram but it would overclock pretty well with 4GB. I was told that it is harder to OC with more than 4GB of ram.
RAM shouldn't be an issue at all. Changing the multiplier changes the CPU clock and thats it, the RAM speed isn't effected at all. VCC and multiplier are all that is really needed to overclock. I've gotten my 2500k to 4.8Ghz at 1.4v, stable for months, without changing anything else.
Thanx to all who answered. I ordered new RAM - 2x2GB sticks - and will try higher clocks when it arrives. I reset everything to defaults and only changed the multiplier to 42x - VCC is set to offset mode and now running 100% stable at 4200Mhz. Note to self: Keep It Simple Stupid!