Skip to main content

System Builder Marathon, Q3 2013: $2550 Performance PC

Overclocking: Hot Air Is Bad, OK?

In the process of upgrading its firmware version 2.40 to support Ivy Bridge-E processors, ASRock unfortunately broke the overclocking functions of its X79 Extreme6. I could set any idle multiplier I wanted, but applying even the smallest load reverted back to Intel's default Turbo Boost ratios, even with Turbo Boost, EIST, and C-states disabled. And since the new motherboard firmware contains new Management Engine firmware, ASRock removed all previous versions from its servers.

I searched online for a rollback and found v.2.20 on a junk-ware site. It was also the Windows-executable version. I tried it in spite of the Management Engine, Windows-executable, and questionable source risks. I got a scare when the system wouldn’t boot, but disconnecting the power and engaging the CLR_CMOS button got the system back on track. Not recommended!

I was able to get the system stable at 1.35 V and 4.6 GHz for a few minutes before thermal throttling took over. Stepping back to 1.30 V and 4.4 GHz worked for a few more minutes, but again reached a thermal ceiling. Very warm air pouring very slowly off the back of a very large cooler in an open system was a sign. This giant, top-rated sink needed faster fans to cope with our processor’s severe thermal issues. I backed down to 4.2 GHz and 1.25 V.

Note that the 1.35 V RAM is not overclocked, even though I increased its voltage. Though it passed all of our previous stability tests at XMP defaults, our AVX-optimized Prime95 workload revealed that it wasn’t completely stable at anything less than 1.46 volts. Pushing past 1.56 volts didn’t offer any stability improvements, and the overclocking window between those two voltage levels was less than 100 MHz.

The fan profile for these EVGA GeForce GTX 760 graphics cards appears to push maximum speed at 80° Celsius, which seems like a great place to leave things. The middle card always ran the hottest, of course. Initially able to run the system for over an hour at 1200 MHz GPU and GDDR5-7760, consecutive gaming runs beyond that point forced me to spend several more hours lowering its overclock and retesting. All-day stability was eventually revealed at 1130 MHz GPU and GDDR5-6680.

Thomas Soderstrom is a Senior Staff Editor at Tom's Hardware US. He tests and reviews cases, cooling, memory and motherboards.