|AMD FX-8350 Vishera Desktop Processor|
|Reviews - Featured Reviews: Processors|
|Written by David Ramsey|
|Tuesday, 23 October 2012|
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AMD FX-8350 Overclocking
Like Intel's Sandy Bridge, AMD's new Piledriver processors are fabricated on a 32nm process. This means they use less power and generate less heat than the older Phenom II CPUs, which were based on a 45nm process. Of course Intel has since moved on to a 22nm process with their Ivy Bridge CPUs, but enthusiast hopes for new overclocking records were dashed when testing showed that the Ivy Bridge CPUs overclocked no better than-- and in most cases not as well as-- Sandy Bridge. This leaves an opening for AMD, who has promised improved overclocking with this generation.
Benchmark Reviews was able to overclock our original FX-8150 Bulldozer-architecture CPU to 4.8GHz. The Piledriver-based FX-8350 did even better, chewing through our benchmark suite at a dead stable 5GHz with the help of a Corsair H100 water cooling system. To reach this overclock I had to set the CPU voltage to 1.48V and adjust all of the power/VRM settings on the ASUS Crosshair V Formula motherboard to their maximum. CPU temperatures peaked at 58 degrees Celsius at an ambient temperature of 23 degrees. While many overclockers prefer to disable some cores to reach the maximum possible GHz, I prefer to leave all cores enabled as I did here.
It's not clear how much overclocking headroom remains in the FX-8350 for exploitation by more exotic cooling methodologies. When the FX-8150 was introduced, AMD's reviewers guide gave a range of overclocking targets for air, water, and liquid nitrogen cooling; this time around, they simply said 5GHz should be possible for many processors using a water cooler, and it seems they were right. I was able to boot into Windows at 5.1GHz but most benchmarks would crash after a short time.
Intel's newer chipsets derive most system clocks from the base clock, so the classic overclocking mechanism of raising the base clock no longer works, since doing so raises every other clock in the system (memory, PCI-E, etc.). This typically means that you can raise the base clock by 3-5MHz before encountering crashes, leaving adjusting the multiplier as the single overclocking mechanism. AMD 990FX systems, on the other hand, are built "the old fashioned way", and so raising the HyperTransport clock remains a viable option for those sub-50MHz increments if you're working to get the last few MHz.
The chart below shows how overclocking affected the 8350's performance on each benchmark, with the stock clocked benchmark score normalized to 1.0 and the overclocked benchmark score represented as how much faster it was than the base clocked benchmark.
The FX-8350 can boost its clock speed to 4.2GHz under normal use, and my 5GHz overclock represents a 19% boost, so a 14% performance improvement isn't too bad although I'd hoped for some more.