An assessment of the different P67 motherboards I've used: http://forums.overclockersclub.com/index.php?showtopic=184385
Also, a guideline to note: http://hardforum.com/showthread.php?t=1578688
Here's a great thread to read for overclocking the i7 2600k on the ASUS P8P67: http://hardforum.com/showthread.php?t=1578110
Note: I run these tests with 16GB memory and the latest BIOS versions when possible. When you overclock to higher CPU overclocks, you also need to adjust for VCCIO voltage. Once I hit 4.9GHz, I have to adjust my VCCIO to 1.1V's or I will get mem errorrs or BSOD's.
BIOS Settings [ASUS P8P67 Deluxe BIOS 1305 (best BIOS version for overclocking before the B3 revision, done with offset voltages) and 1503 (needs higher voltages for overclocks, done with manual voltages) + Sabertooth P67 BIOS 1502] + ASUS P8Z68-V Pro BETA BIOS 0651:
Note: All ASUS P and Z boards have pretty much the same settings
Internal PLL Overvoltage = Auto
LLC = Ultra High
VRM Frequency = 350
Phase Control change to = Extreme
Duty Control change to = Extreme
CPU Spread Spectrum = Disabled
Here's a great thread to read for overclocking the i7 2600k on the GIGABYTE GA-P67A-UD7-B3: http://www.overclock.net/intel-general/910467-ultimate-sandy-bridge-oc-guide-p67a.html
BIOS Settings (GIGABYTE GA-P67A-UD7-B3):
Internal CPU PLL Overvoltage = Enabled
Real-Time Ratio Changes in OS = Disabled (Optional)
Intel® Turbo Boost Tech. = Disabled
CPU Enhanced Halt (C1E) = Disabled
C3/C6 State Support = Disabled
CPU Thermal Monitor = Disabled
CPU EIST Function = Disabled
Multi-Steps Load-Line = Level 6
BIOS Settings (MSI P67A-GD65):
Overclocking on the MSI P67A-GD65 (B3)
Note: Intel specs the TCase is 72.6C, so I'm stopping from overclocking further unless I want to adjust for better cooling. My goal is to run it 24/7 stable (benchmark overclocking is another story).
Safest 24/7 overclock going by Intel's specifications (CPU Voltage not going above 1.35V and temps below 72.6C):
Cooling = 120.4 Swiftech Ultima XT Pull (5v) Max - MCP655 Rev. B
i7 2600k | ASUS P8P67 Deluxe | 4.4GHz (44 x 100Mhz) @ 1.345V BIOS 1502; 1.336V - 1.352V CPU-Z | Prime 95 max temps = 60C | Tests Passed
Cooling = 120.4 Swiftech Ultima XT Pull (5v) Max - MCP655 Rev. B
i7 2600k | ASUS Sabertooth P67 | 4.4GHz (44 x 100Mhz) @ 1.345V BIOS; 1.344V - 1.352V CPU-Z | Prime 95 max temps = 58C | Tests Passed
Cooling = 120.4 Swiftech Ultima XT Pull (5v) Max - MCP655 Rev. B
i7 2600k | GIGABYTE GA-P67A-UD7-B3 | 4.4GHz (44 x 100Mhz) @ 1.340V BIOS; 1.344V - 1.352V CPU-Z | Prime 95 max temps = 60C | Tests Passed
Cooling = 120.4 Swiftech Ultima XT Pull (5v) Max - MCP655 Rev. B
i7 2600k | ASUS P8P67 Deluxe | 4.5GHz (45 x 100Mhz) @ - .010 BIOS 1305; 1.336V - 1.352V CPU-Z | Prime 95 max temps = 58C | Tests Passed
Cooling = 120.2 Swiftech Ultima XT Push/Pull (5v) Max - MCP655 Rev. B
i7 2600k | ASUS P8P67 Deluxe | 4.5GHz (45 x 100Mhz) @ - .010 BIOS 1305; 1.336V - 1.352V CPU-Z | Prime 95 max temps = 60C | Tests Passed
Cooling = 120.2 Swiftech Ultima XT Push/Pull (5v) Max - MCP655 Rev. B
*i7 2600k | ASUS P8P67 Deluxe | 4.6GHz (46 x 100Mhz) @ 1.350 BIOS 1305; 1.336V - 1.352V CPU-Z | Prime 95 max temps = 63C | Tests Passed
Cooling = 120.2 Swiftech Ultima XT Push/Pull (5v) Max - MCP655 Rev. B
i5 2500k | ASUS P8P67 Deluxe | 4.6GHz (46 x 100Mhz) @ - .010 BIOS; 1.336V - 1.352V CPU-Z | Prime 95 max temps = 62C | Tests Passed
Cooling = 120.2 Swiftech Ultima XT Push/Pull (5v) Max - MCP655 Rev. B
i5 2500k | ASUS P67 Sabertooth | 4.7GHz (47 x 100Mhz) @ - .010 BIOS 1850; 1.336V - 1.352V CPU-Z | Prime 95 max temps = 64C | Tests Passed
24/7 overclocks going past Intel's Vcore recommendation (CPU voltage 1.35V+, but temps still below 72.6C):
Cooling = 120.4 Swiftech Ultima XT Pull (5v) Max - MCP655 Rev. B
i7 2600k | GIGABYTE GA-P67A-UD7-B3 | 4.5GHz (45 x 100Mhz) @ 1.350V BIOS; 1.356V - 1.368V CPU-Z | Prime 95 max temps = 62C | Tests Passed
Cooling = 120.4 Swiftech Ultima XT Pull (5v) Max - MCP655 Rev. B
i7 2600k | ASUS Sabertooth P67 | 4.5GHz (45 x 100Mhz) @ 1.350V BIOS; 1.352V - 1.360V CPU-Z | Prime 95 max temps = 60C | Tests Passed
Cooling = 120.2 Swiftech Ultima XT Push/Pull (5v) Max - MCP655 Rev. B
i7 2600k | ASUS P8P67 Deluxe | 4.6GHz (46 x 100Mhz) @ + .005 BIOS 1305; 1.360V - 1.368V CPU-Z | Prime 95 max temps = 66C | Tests Passed
Cooling = 120.2 Swiftech Ultima XT Push/Pull (5v) Max @ 20% - 25% pump speed - MCP35x
i7 2600k | ASUS P8P67 Deluxe | 4.6GHz (46 x 100Mhz) @ + .005 BIOS 1305; 1.360V - 1.368V CPU-Z | Prime 95 max temps = 66C | Tests Passed
Cooling = 120.4 Swiftech Ultima XT Pull (5v) Max - MCP655 Rev. B
i7 2600k | ASUS P8P67 Deluxe | 4.6GHz (46 x 100Mhz) @ 1.385V BIOS 1502; 1.368V - 1.384V CPU-Z | Prime 95 max temps = 64C | Tests Passed
Cooling = 120.4 Swiftech Ultima XT Pull (5v) Max - MCP655 Rev. B
i7 2600k | ASUS Sabertooth P67 | 4.6GHz (46 x 100Mhz) @ 1.375V BIOS; 1.376V - 1.384V CPU-Z | Prime 95 max temps = 66C | Tests Passed
Cooling = 120.2 Swiftech Ultima XT Push/Pull (5v) Max - MCP655 Rev. B
*i7 2600k | ASUS P8P67 Deluxe | 4.7GHz (47 x 100Mhz) @ + .010 BIOS 1305; 1.360V - 1.376V CPU-Z | Prime 95 max temps = 65C | Tests Passed
Cooling = 120.4 Swiftech Ultima XT Pull (5v) Max - MCP655 Rev. B
i7 2600k | ASUS P8P67 Deluxe | 4.7GHz (47 x 100Mhz) @ + .070 BIOS 1305; 1.416V - 1.432V CPU-Z | Prime 95 max temps = 68C | Tests Passed
Cooling = 120.2 Swiftech Ultima XT Push/Pull (5v) Max @ 20% - 100% pump speed - MCP35x
i7 2600k | ASUS P8P67 Deluxe | 4.7GHz (47 x 100Mhz) @ + .040 BIOS 1305; 1.392V - 1.400V CPU-Z | Prime 95 max temps = 68C | Tests Passed, but probably wasn't 100%?
Cooling = 120.4 Swiftech Ultima XT Pull (5v) Max - MCP655 Rev. B
i7 2600k | ASUS P8P67 Deluxe | 4.7GHz (47 x 100Mhz) @ 1.435V BIOS 1502; 1.424 - 1.432V CPU-Z | Prime 95 max temps = 70C | Tests Passed
Cooling = 120.4 Swiftech Ultima XT Pull (5v) Max - MCP655 Rev. B
i7 2600k | ASUS Sabertooth P67 | 4.7GHz (47 x 100Mhz) @ 1.415V BIOS; 1.416V - 1.424V CPU-Z | Prime 95 max temps = 68C | Tests Passed
Cooling = 120.2 Swiftech Ultima XT Push/Pull (5v) Max - MCP655 Rev. B
i5 2500k | ASUS P67 Sabertooth| 4.8GHz (48 x 100Mhz) @ + .005 BIOS 1850; 1.384V - 1.392V CPU-Z | Prime 95 max temps = 68C | Tests Passed
Cooling = 120.2 Swiftech Ultima XT Push/Pull (5v) Max - MCP655 Rev. B
*i7 2600k | ASUS P8P67 Deluxe | 4.8GHz (48 x 100Mhz) @ + .055 BIOS 1305; 1.408V - 1.416V CPU-Z | Prime 95 max temps = 69C | Tests Passed with as low as .010 BIOS, but idle bug until .050
Cooling = 120.4 Swiftech Ultima XT Pull (5v) Max - MCP655 Rev. B
i7 2600k | ASUS P8P67 Deluxe | 4.8GHz (48 x 100Mhz) @ + .110 BIOS 1305; 1.464 - 1.472V CPU-Z | Prime 95 max temps = 71C | Tests Passed
Cooling = 120.4 Swiftech Ultima XT Pull (5v) Max - MCP655 Rev. B
i7 2600k | ASUS P8P67 Deluxe | 4.8GHz (48 x 100Mhz) @ 1.475V BIOS 1502; 1.464V - 1.480V CPU-Z | Prime 95 max temps = 72C | Tests Passed
Cooling = 120.4 Swiftech Ultima XT Pull (5v) Max - MCP655 Rev. B
i7 2600k | GIGABYTE GA-P67A-UD7-B3 | 4.8GHz (48 x 100Mhz) @ 1.455V BIOS; 1.452V - 1.464V CPU-Z | Prime 95 max temps = 69C | Tests Passed
Cooling = 120.4 Swiftech Ultima XT Pull (5v) Max - MCP655 Rev. B
i7 2600k | ASUS Sabertooth P67 | 4.8GHz (48 x 100Mhz) @ 1.455V BIOS; 1.456V - 1.464V CPU-Z | Prime 95 max temps = 69C | Tests Passed
Cooling = 120.2 Swiftech Ultima XT Push/Pull (5v) Max - MCP655 Rev. B
*i7 2600k | ASUS P8P67 Deluxe | 4.9GHz (49 x 100Mhz) @ + .040 BIOS 1305; 1.400V - 1.416V CPU-Z | Prime 95 max temps = 69C | Tests Failed with memory warnings and errors, no luck with changing DRAM voltages and loosening speeds and timings. CPU is stable at this voltage, and possibly lower.)
24/7 overclocks going past Intel's Vcore recommendation (CPU voltage 1.35V+, but temps still below 72.6C):
Cooling = 120.2 Swiftech Ultima XT Push/Pull (5v) Max - MCP655 Rev. B
*i7 2600k | ASUS P8Z68-V Pro | 4.8GHz (48 x 100Mhz) @ + .055 BIOS BETA BIOS 0651; 1.416V - 1.424V CPU-Z | Prime 95 max temps = 69C | Tests Passed
Cooling = 120.4 Swiftech Ultima XT Push/Pull (5v) Max - MCP655 Rev. B
*i7 2600k | ASUS P8Z68-V Pro | 4.9GHz (49 x 100Mhz) @ 1.465 BIOS BETA BIOS 0902; 1.456V - 1.464V CPU-Z | Prime 95 max temps = 72C | Tests Passed (used 2 x 4GB RAM)
Cooling = 120.2 Swiftech Ultima XT Push/Pull (5v) Max - MCP655 Rev. B
i5 2500k | ASUS P8Z68-V Pro | 4.9GHz (49 x 100Mhz) @ 1.480 BIOS 0902; 1.464V - 1.472V CPU-Z | Prime 95 max temps = 69C | Tests Passed
If you get BSOD's, here's a good list of what the codes might mean: http://www.overclock.net/intel-cpus/935829-overclockers-bsod-code-list.html
Just for comparison:
i5 2500k @ 4.6GHz Cinebench 11.5 = 7.28 points
1090T @ 4.2GHz Cinebench 11.5 = 7.35 points
i7 950 @ 4.37GHz Cinebench 11.5 = 7.38 points
i5 2500k @ 4.7GHz Cinebench 11.5 = 7.45 points
i5 2500k @ 4.7GHz Cinebench 11.5 = 7.51 points
i7 2600k @ 4.4GHz Cinebench 11.5 = 8.51 points
i7 2600k @ 4.5GHz Cinebench 11.5 = 8.72 points
i7 2600k @ 4.6GHz Cinebench 11.5 = 8.91 points
i7 2600k @ 4.7GHz Cinebench 11.5 = 9.02 points
i7 2600k @ 4.8GHz Cinebench 11.5 = 9.29 points
i7 2600k @ 4.8GHz Cinebench 11.5 = 9.35 points (different memory, and at 1T instead of 2T)
i7 2600k @ 4.9GHz Cinebench 11.5 = 9.14 points (2x4GB memory at 1T instead of 4x4GB)
i7 2600k @ 4.9GHz Cinebench 11.5 = 9.51 points (memory at 1T)
i5 2500k Overclocks
Nuclear - 24/7 overclock is 5.0Ghz @ 1.37v; highest overclock is 5.3Ghz @ 1.47v
NoKz - 24/7 overclock is 5.0Ghz @ 1.44v
Ecofriendly - 24/7 overclock is 4.7Ghz @ 1.385v
i7 2600k Overclocks
MJCRO - 24/7 overclock is 5.0Ghz @ 1.41v
RJR - 24/7 overclock is 5.0Ghz @ 1.48v
LuckyDeath - 24/7 overclock is 4.8Ghz @ 1.39v
leezaal - 24/7 overclock is 4.7Ghz @ 1.39v
jackbrennan2008 - 24/7 overclock is 4.5Ghz @ 1.265v; highest overclock is 5.5Ghz @ 1.55v
usaweapon777 - 24/7 overclock is 4.7Ghz @ 1.42v
Rickytuk - 24/7 overclock is 4.5Ghz @ *1.82v
iskout - 24/7 overclock is 4.5Ghz @ 1.32v
andywebb22 - 24/7 overclock is 4.5Ghz @ 1.32v