AMD Vishera - FX 8350 Performance Review

Company: AMD
Author: James Prior
Editor: Charles Oliver
Date: October 23rd, 2012

Piledriver FX

The AMD FX 8350 is a quad module, eight core processor sporting HyperTransport 3.0 and turbo core 3.0 features. The significant change from the FX 8150 is the increase is clock speed, the base clock is now 4Ghz instead of 3.6GHz, and the four core turbo (an improved feature) is the same 4.2GHz, all of which is done in the same 125W TDP and on the same 32nm SOI process from GlobalFoundries.

Piledriver Die

The improvements start at the front end, with the hybrid predictor augmented with a 2nd level predictor to help keep decoding of instructions flowing smoothly. The two integer schedulers and single floating point schedulers have been reworked, adding a hardware divider to improve concurrency and both integer cores using the combination FPU. The L1 table look up buffer has been doubled in size, and the L1 pre-fetcher has been breathed on to speed up operation as well. Clearly AMD knew where some of the pain points with Bulldozer were refining the design before the first product even hit the stores, courtesy of the nature of CPU architecting and product production - 12 month validation cycles mean you can have product 99% finished a year ahead of launch, and now we're looking at 2011's Bulldozer revision here at the end of 2012.

Enhanced Architecture

Another area of improvement for Piledriver is power management, with Piledriver estimated to offer 10% lower dynamic power than Bulldozer, with faster power gating switching - low power and sleep states for cores are going to be enabled faster, saving energy quicker. These improvements show the most benefit in the lower TDP chips, allowing higher base frequencies as evidenced in the Trinity notebook APUs. For desktop FX, this increased thermal budget is something that can be leveraged by Turbo Core 3.0 for longer periods of boost clocks, as well as higher base clocks - this is AMD's first 4GHz processor.

Positioned against Core i5

The upshot is that the FX 8350 should be faster than the FX 8150 and AMD is positioning it against the Core i5 3570K, kinda. AMD's own benchmarks show wins and losses against that product, but if you want an overclockable Intel processor you're choices are the Sandy Bridge i5 2500K at ~$220USD or the Ivy Bridge i5 3570K at ~$230USD. At $195USD SEP the FX 8350 is 18% cheaper than the Core i5 3570K, so if it performs at 82% or better of the i5 3570K then AMD are in the right ball park for performance per dollar, or bang for buck. With a rated TDP of 125W we can be fairly certain that performance per watt is going to be a win for Intel - the 77W Ivy Bridge and 95W Sandy Bridge processors are going to be more efficient in outright terms but more expensive, too. AMD also tell us we can expect to see a 15% performance increase over the FX 8150, including up to 20%-25% more performance in gaming.