|BIOS Frequency and Voltage settings (for overclocking)|
|ASRock Z87 OC Formula||Asus Maximus VI Formula||Gigabyte Z87X-UD5H||MSI Z87 MPower Max|
|Base Clock||90-300 MHz (0.1 MHz)||60-300 MHz (0.1 MHz)||80-267 MHz (0.01 MHz)||90-300 MHz (0.06 MHz)|
|CPU Multiplier||8.0-120x (1x)||8.0-80x (1x)||8-80x (1x)||8-80x (1x)|
|DRAM Data Rates||800-4000 (200/266.6 MHz)||800-3200 (200/266.6 MHz)||800-2933 (200/266.6 MHz)||800-3200 (200/266.6 MHz)|
|CPU Vcore||0.80-2.00V (1 mV)||0.001-1.92V (1 mV)||0.50-1.80V (1 mV)||0.80-2.10V (1 mV)|
|VCCIN||1.20-2.30v (10 mV)||0.80-2.44V (10 mV)||1.00-2.91V (10 mV)||1.20-3.04V (1 mV)|
|PCH Voltage||0.97-1.32 V (5 mV)||0.70-1.80 V (6.25 mV)||0.65-1.30 V (5 mV)||0.70-1.68 V (10 mV)|
|DRAM Voltage||1.05-2.40 V (6.5 mV)||1.20-2.40 V (5 mV)||1.15-2.10 V (5 mV)||0.30-2.45 V (15 mV)|
|CAS Latency||4-15 Cycles||1-31 Cycles||5-15 Cycles||4-15 Cycles|
|tRCD||3-31 Cycles||1-31 Cycles||4-31 Cycles||4-31 Cycles|
|tRP||4-31 Cycles||1-31 Cycles||4-31 Cycles||4-31 Cycles|
|tRAS||9-63 Cycles||1-63 Cycles||5-63 Cycles||9-63 Cycles|
We see base clock frequency adjustments up to 300 MHz for some motherboards, but know that most Haswell-based processors are limited to less than 10% over-stock. That would be 110 MHz when using a 100 MHz strap, or 183 MHz when using a 166.7 MHz strap.
We couldn’t get any of the motherboards in this review to give us exactly 1.25 V, and anything above 1.27 V caused our CPU to overheat. ASRock got closest to 1.27 V, so that possibly helps explain its 10 MHz lead. MSI had the least over-voltage of the group, but the difference of a few millivolts probably shouldn’t be attributable for this much of an overclocking deficit.
With the CPU's voltage increased and multiplier reduced, ASRock returns the highest base clock. Asus also offers special BCLK overclocking profiles for unlocked CPUs, but our real concern is how far the 100 MHz strap might push a locked CPU.
Gigabyte takes a fairly big dip in DRAM overclocking, though our recent test showed that data rates beyond DDR3-2133 aren’t particularly useful anyway, even if you're using integrated graphics. Then again, neither is BCLK overclocking when the only CPU models that support boot strap changes are already multiplier-unlocked. ASRock’s lead and/or tie across all three disciplines is noteworthy in that the Z87 OC Formula had no stability deficits.