Which Heat Sink Best Contends With Haswell's Heat Problems?
Here's the bombshell we figured out from today's testing: for overclocking, a quad-core Haswell-based processor at 22 nm requires more cooling than a six-core Sandy Bridge-E CPU at 32 nm, even though its lower power consumption produces less heat. The back-up for this is that two of the coolers from our Sandy Bridge-E cooling round-up re-appeared today with far worse apparent performance. Most overclockers blame Intel’s newer integrated heat spreader and transfer material for this discrepancy. These days, cheap paste replaces solder for connecting the CPU die to the spreader.
Cross-compatibility between LGA 1150, 1155, and 1156 sinks theoretically makes it possible for us to test dozens of heat sinks and fans. Unfortunately, most solutions are too small to cope with the heat issues an overclocked Haswell-based CPU suffers. Since Haswell has the smoothest thermal throttling implementation I’ve yet experienced, I set a simple rule that any cooler that hit its threshold temperature (100° Celsius) would be disqualified from final consideration. That guideline prevented the submission of many samples, and even knocked three of the coolers we tested out of contention. But it left a hole wide open for one cooler to slip through at a maximum core temperature of 75° over ambient. Nobody should be expected to keep the inside of their case cooler than 25°.
With a moderate price and moderate cooling capability, Scythe’s Ashura SCASR-1000 would have received our “Smart Buy” award if we didn’t need to warn you to keep your case below 25° internally. We'll save you the conversion. That's 77° Fahrenheit inside your case, just to run a Core i7-4770K at 1.25 V. And the company might still have won that award if we lowered our overclocking parameters. We don't think it'd be fair to hand out a prize, since we announced the settings we'd be using during the invite phase. However, if your overclocking expectations are lower than 4.5 GHz, we think you'll be pleased with the Ashura.
The top-performing configuration in our review, Prolimatech’s PRO-GNSS-BK with dual PRO-USV14 fans and PRO-USB-ARMG adapter clips would likewise be a contender for our highest-end “Elite” award, if not for its total build price. If I'm an enthusiast looking for the best of the best, which is what wins an Elite award from us, then I'm going to go with liquid cooling rather than spending a total of $125 on those parts, though we have to give Prolimatech credit for an elite collection of cooling components.
Noctua's NH-U14S isn't the strongest performer qualifying for our stamp of our approval, but it is the least-expensive option able to do what we need it to. Second place on our value charts behind the Ashura, which barely qualifies, the NH-U14S is effective enough to allow a 31° case temperature before our Core i7-4770K at 4.5 GHz started throttling under unusually stressful test loads. In other words, it allows us to get most of our intended performance most of the time.
If that sounds like a half-hearted justification, consider the field and consider our tepid response to Core i7-4770K in the first place. We aren't particularly enthused about Intel's latest effort, but Noctua's NH-U14S makes the best of a difficult situation.