AMD's latest round of Athlon 64 releases marks the debut of Socket 939 -- yet another new pin layout. This gives the chip-maker the chance to introduce dual-channel memory control without impinging on its Opteron server range, which uses Socket 940. Giving Athlon 64s more and faster memory access in turn lets AMD market chips with smaller amounts of Level 2 (L2) cache, without completely compromising their performance.
AMD has announced four new Athlons, three in Socket 939 and one in the older Socket 754 format. The latter, the $710 Athlon 64 3700+, has 1MB of L2 cache and an 800MHz HyperTransport bus, together with a single-channel 64-bit memory interface. It fulfills AMD's promise not to abandon Socket 754 and maintains an upgrade path for existing motherboards. Although there are no more Socket 754 chips on the roadmap at present, AMD is bullish about future products with this layout, with support expected until 2005.
|New AMD processors|
||Athlon 64 FX-53
||Athlon 64 3800+
||Athlon 64 3700+
||Athlon 64 3500+
|Level 2 cache||1MB||512KB||1MB||512KB|
|Memory interface||128 bits||128 bits||64 bits||128 bits|
|HyperTransport bus speed||1GHz||1GHz||800MHz||1GHz|
|Transistor count||105.9 million||68.5 million||105.9 million||68.5 million|
Socket 939: the desktop future
However, AMD is keen to move everyone onto Socket 939, and says that this will be its standard desktop socket for the foreseeable future. The three new chips in this format all have dual-channel 128-bit memory controllers and a 1GHz HyperTransport bus: they are the $500 Athlon 64 3500+, with 512KB of L2 cache; the near-identical $720 Athlon 64 3800+; and the Athlon 64 FX-53 with a full megabyte of L2 cache. This last chip costs $799 -- slightly more than the 3800+ -- and is the CPU that AMD is pitching at overclockers and hard-core gamers.
One of the big advantages of the new format is that it uses non-registered DDR memory. Previously, AMD's dual-channel controllers needed registered memory -- chips that constantly checked for errors. Non-registered memory is faster, easier to overclock and cheaper.
The heat is on
The Athlon 64 3800+ and the FX-53 both have a nominal clock frequency of 2.4GHz, but reports indicate that this has already been pushed up to 2.6GHz by some continental overclockers. At the maximum specified frequency the FX-53 has a design heat dissipation of more than 100 watts, making efficient cooling more important than ever before. However, this is also the first FX part with AMD's Cool'n'Quiet technology, which reduces power consumption by dynamically slowing down unused parts of the processor during operation.
Socket 939 motherboards are due from the usual suspects -- Asus, MSI, Gigabyte -- with a choice of nVidia, SIS and Via chipsets, with companies like Shuttle producing small-form-factor systems.