AMD Piledriver FX “Vishera” CPU Review – What Bulldozer Should Have been

AMD Piledriver FX Review – This could be it for AMD. One last ‘hurrah’. After their Q3 2012 financials came out showing a net loss of $157 million, they began a restructuring phase, immediately laying off  15% of their employees. In other words, they are going to change how they do business, and that could very well mean the death of their desktop CPU lineup.

There is no better way to put it – Bulldozer was a flop. It was a hot, power hogging chip that never reached its clock speed goals. Because of that, it couldn’t compete the way it was meant to, and prices were slashed. And even then, its performance relative to similarly priced competition didn’t make up for the heat and noise it would generate. It only got worse when Ivy Bridge was launched, with even better per-clock performance and lower power consumption.

The Bulldozer design was refreshed as Piledriver, and AMD made several key improvements in order to get power consumption down, and performance up. We already reviewed Trinity, their all-in-one APU solution that uses two Piledriver cores in conjunction with a Radeon GPU, and found it to be favorable over its main competition (Intel’s Core i3 3220). But a 95W CPU with built-in graphics isn’t exactly what most enthusiasts are interested in. No, we want a powerful CPU to work with a discrete video card, is tweakable, and won’t break the bank. For the past while, that has meant the Intel Core i5 CPU, such as the Ivy Bridge based i5 3570K, and the Sandy Bridge based i5 2500K.

AMD is aiming directly for that CPU, and directly for you, the enthusiast. A cynical person might say that the fact that they aren’t even going for the Core i7 means they still haven’t gotten their act together, and Piledriver isn’t enough of an improvement over Bulldozer. To me, it doesn’t matter, because the Core i5 was always more compelling than the i7 anyway. It offers almost the same performance at 2/3 the price.

Today we’re going to find out if AMD has what it takes to compete in the enthusiast market once again. We will take most of the new lineup of FX CPUs codenamed “Vishera”, and pit it directly against similarly priced CPUs from Intel. As you know, our method of testing will tell us the full story, and by the end we’ll know if Piledriver is just another sad chapter in AMD’s recent history, or the beginning of a turnaround for the company.

How Piledriver Works

Most of Piledriver’s improvements over Bulldozer take place on a micro level; there isn’t a lot to talk about in regards to new functions, instructions, or hardware layout. It really is “what Bulldozer should have been”.

Piledriver’s improvements over Bulldozer

As you can see, most of the highlighted areas are “improved” rather than “new”. A better prefetcher, better scheduler, branch predictor, and a larger L1 cache all work together to improve the per-clock performance over Bulldozer. It is no secret that Bulldozer was simply a server chip forced to perform as a desktop chip, but AMD took the time to make the changes needed to make Piledriver more suitable for desktop use. The ‘optimized page translation reload’ and L2 efficiency improvements refer to this.

As far as all new additions go, two ISA extensions were added. As you may recall, Bulldozer added FMA4 support, but Intel decided to go with FMA3. Because the two aren’t directly interchangeable, AMD had to follow suit and add FMA3 support to Piledriver (don’t expect Intel to add FMA4, although Piledriver has retained it). Also, F16C – introduced with Ivy Bridge – was added to Piledriver. This adds the ability to quickly convert between 16- and 32- bit floating point data formats.

This should all add up to a 15% improvement over the FX-8150, while at the same time using less power.

No New Platform Needed

AMD has done a pretty good job at maintaining platform compatibility across new CPU launches. The new Vishera Piledriver CPUs run on the AM3+ platform, just like Zambezi Bulldozer chips before it.  In fact AMD models going all the way back to Socket AM3 chips like the Phenom II and Sempron will work on the same motherboards. The Gigabyte board used for testing didn’t even need a BIOS update to fully support the new CPU.

Because of this, 990FX remains the top end chipset for this CPU. It is a pretty decent chipset, despite being over a year old now.

990FX has a few key advantages over Intel’s top desktop chiset, Z77. Although the PCI-E version is still Gen 2, both are full x16 lanes. Ivy Bridge and Z77 only offer up to two 8x lanes. Secondly, it supports size SATA 3.0 ports, where Intel only offers two. Finally, the chipset officially supports DDR3 1866 MHz ram, while Z77 tops out at 1600 MHz officially.

Some disadvantages are the lack of native USB 3.0 support in the chipset, which Z77 added, and a built-in SSD cache system. In my opinion, adding a small SSD cache to your system is all but a necessity, considering how much it improves every-day performance, and SSD prices continue to drop. For most people, using an SSD cache is just as good as using a dedicated SSD. With Z77, you get this right out of the box – simply add your SSD, and enable Smart Response Technology. With 990FX you will have to use a Solid State Cache product like the Crucial Adrenaline, which comes with its own caching software. Thankfully, this software works just as well as Intel’s; the drives just cost a little more.