ASRock includes several handy integrated overclocking profiles, including 4.6 and 4.4 GHz. The lower of those two profiles worked most of the time, switching core voltage between 1.05 and 1.28 V under various loads. That would have been perfect, except that the system did occasionally (and rarely) crash. We decided to use manual settings to achieve similar results, without any occasional instability.
Our memory willingly complied with an increase from its standard 1,600 MT/s data rate to DDR3-2133. Further down the BIOS page, we set a fixed CPU core of 1.28 V.
When paired with the Core i5-3570K CPU, the Z77 Extreme4’s “Level 1” Load-Line Calibration provided an extremely stable voltage range between the set 1.28 and a maximum of 1.296 V. Keeping the processor below 1.30 V provides the added insurance of longevity.
We were actually able to hold 4.5 GHz for extended benchmarking sessions, without overheating, but again faced occasional and almost mysterious instability. Unwilling to push past 1.30 V, we settled for 4.40 GHz.
We would have expected low-profile 1.35 V DIMMS to get hot at 1.60 V, but Crucial’s Ballistix Tactical LP had no such issues. That extra voltage helped us retain stock 9-9-9-24 timings at this 33% overclock, edging out the CAS 10 timings we achieved last quarter using standard-voltage modules at the same DDR3-2133 data rate.
PowerColor’s Tahiti-LE-equipped Radeon HD 7870 reached 1,200 MHz GPU and GDDR5-6400 fairly easily, though we did need to change the maximum fan speed temperature from 90° to 80° Celcius. Running short of time for fine-tuning, we tried adding 50 MHz, only to have one of our games crash.