In light of revelations concerning Intel’s Ivy Bridge heat spreader application, our strategy for this machine’s overclock would be to keep core voltage low, external cooling high, and hope for the best.
And then the best actually happened: we were able to reach 4.6 GHz with minimal fuss.
We did face a fairly difficult heat transfer issue, limiting our voltage tolerance to 1.25 V. Though 4.7 GHz would have been possible at 1.28 V, the added heat caused the Core i7-3770K to throttle during our combined load (CPU and GPU) tests.
We were able to push our DDR3-1600 CAS 8 kit to DDR3-2000 CAS 8 after making minor alterations to its tRCD and tRP. We tested various tRAS values between 16 and 24 cycles and, finding no performance difference, thought the lower number looked better.
This Asus graphics card comes with an extremely nice and well-detailed overclocking utility, exceeding the adjustability of MSI’s universal Afterburner utility. Unfortunately, Asus' software didn’t make the card overclock any higher, and we couldn’t find temperature-based fan controls. Not willing to tolerate a high noise level from an idle card, we made the switch.
The GeForce GTX 680 uses GPU Boost to increase frame rates when the headroom provides for it, scaling back under more thermally-taxing workloads. Increasing the card’s power limit also increases its ability to hold boost frequency, though simultaneously increasing the likelihood that the GPU will encounter instability.
Given the option of a higher frequency that doesn’t hold up well or a moderate frequency that’s usually there when needed, this editor chose the latter. The card’s Power Limit was set to maximum, which reduced its GPU overclock to a mere 61 MHz over Asus’ already-high 1201 MHz boost frequency.
The graphics RAM overclock was far more interesting, jumping from GDDR5-6008 to an incredible GDDR5-7204. Thanks Asus!
Our overclock did require a little fuss over fan settings. MSI Afterburner provides a custom fan profile setting that can be arranged to anything from a straight line to a fancy multi-point curve. We used a standard slope, allowing the card to be quiet at low loads and noticeably loud after extended periods at full load.