As for Athlon 64 FX, the idea to introduce a product like that occurred to AMD just recently. AMD decided to release an extremely fast gaming solution because the performance of the regular Athlon XP working at 2GHz was not high enough, as AMD desired it to be. Athlon 64 FX is a full analogy to AMD Opteron processor with the dual-channel memory controller. It even uses the same processor Socket 940 as Opteron CPU. The only thing that has become really different is the die marking. That is why Athlon 64 FX inherited some server features from the Opteron family. In particular, Athlon 64 FX requires Registered memory, which is really weird to tell the truth. Also AMD mentioned the support of Registered DDR400 SDRAM, although there is nothing special about it, actually: Opteron can also work with this memory type. It is quite a different story that Registered DDR400 hasn’t been yet approved by JEDEC and there are really very few memory modules like that available in the market today: basically you can count them with the fingers of one hand. However, the launching of Athlon 64 FX will definitely push many memory makers to start making these modules. For example, today together with the Athlon 64 FX processor announcement, Kingston launched their new Registered DDR400 memory, which will sell among HyperX products. And a few days ago OCZ also announced that they begin shipping memory modules like that.
Athlon 64 and Athlon 64 FX have also acquired a few long awaited changes of the package design and anti-burn protection. First of all, I would like to mention a special lid that protects the CPU die against physical damage during cooler installation and removing. Moreover, besides the built-in thermal diode, Athlon 64 FX and Athlon 64 have finally got their own anti-overheating protection circuit. Although, it doesn’t bring anything brand new to the idea behind it: if the CPU reaches certain critical temperature, it simply shuts down. Anyway, it is very pleasing that AMD has finally taken note of the reliability issues, which have been encountered by their Athlon and Athlon XP CPUs pretty often.
So, let’s sum up everything we have just said about the new Athlon 64 FX-51 and Athlon 64 3200+ in a table below. For a more illustrative picture here are the results for Athlon XP 3200+ as well:
Athlon 64 FX-51
Athlon 64 3200+
Athlon XP 3200+
Number of transistors
Integrated memory controller
Supported memory types
Registered DDR400/ DDR333/ DDR266 SDRAM
DDR400/ DDR333/ DDR266 SDRAM
SIMD instructions support
AMD64 technology support
* - Note that although the memory of Athlon 64 and Athlon 64 FX is clocked relative to the core frequency, the actual memory frequencies in this case make 100, 129.4, 157.1 and 200MHz.