Closer Look at FX Processor Family on Piledriver Microarchitecture
AMD sent out the top Vishera FX-8350 processor for the reviews of the new Socket AM3+ platform on Piledriver microarchitecture. However, in fact, the refreshed line-up includes four processor models: the above mentioned FX-8350, and slower modifications with lower clock frequencies featuring eight, six and four physical cores. They are all similar in some way: following the long-time tradition AMD sticks to unification within their product line-ups and uses a unified semiconductor dies in their Vishera processors. It consists of four dual-core modules and an 8 MB L3 cache. This semiconductor Vishera die consists of 1.2 billion transistors and is 315 sq.mm big.
However, the junior processors models do not use this entire die. The manufacturer may disable one or two dual-core modules, or cut off some of the L3 cache memory. On the one hand, this allows to easily create an entire line-up of diverse products, and on the other hand, the manufacturer gets the opportunity to put partially defective dies to good use. AMD varied the number of active dual-core modules in their previous generation Zambezi processors creating six-core FX-6000 and quad-core FX-4000 models. The differentiation in Vishera family has become much deeper: they also began to cut off half of the L3 cache memory. As a result, AMD FX processors family on the new Piledriver microarchitecture currently looks as follows:
Let’s take a closer look at the members of this family.
We have already discussed this flagship Vishera processor in an individual review. Nevertheless, I would like to remind you that it represents the most feature-rich modification of a Socket AM3+ processor available today. It means that FX-8350 has eight paired cores and 8 MB L3 cache. Its nominal clock frequency is set at 4.0 GHz, so the manufacturer has every right to claim that this is the first desktop processor to hit 4 GHz frequency level.
AMD believes that FX-8350 is a direct competitor to Intel Core i5-3570K, but in our opinion, this is an excessively optimistic prognosis. Nevertheless, the official price of the new FX processor is set at $195, thus allowing to compare it against slower Core i5 models on Ivy Bridge microarchitecture. Of course, the new AMD processor looks considerably more confident against those.
Unfortunately, we do not know yet how fast AMD is planning on increasing the clock speeds for their Vishera processors. It is very likely that FX-8350 will remain a flagship product for a while. Especially, since they have already postponed the launch of the next microarchitectural iteration codenamed Steamroller until 2014.
Obviously, not all Vishera semiconductor dies can work at 4.0 GHz frequency and 125 W max TDP, because they are manufactured using not the most advanced 32 nm process. Therefore, the top eight-core processor in AMD’s line-up is also accompanied by a slower modification – FX-8320 with similar characteristics, but lower clock speed. In other words, this processor, just like its elder brother, FX-8320, has eight paired cores and an 8 MB L3 cache, but works at 3.5 GHz nominal frequency, which is 500 MHz lower than that of the flagship processor. This processor can only speed up to the desired 4 GHz when you overclock it using Turbo Core technology. Nevertheless, the TDP of the slower Vishera processor still remains at 125 W.
Overall, the characteristics of the new FX-8320 are very similar to those of FX-8150 with Zambezi design. However, its price is set at $169, and it is positioned as a direct competitor to Intel Core i5-3450.