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AMD swaps sockets
After what seems like an eternity, DDR2 finally makes it to the Athlon 64 platform.
Yet another socket change for AMD? The company’s naysayers will run and run with this one, but the truth of the matter is that no one likes a change in socket. It’s annoying for consumers, motherboard manufacturers, system integrators and even the company that makes processor itself. So why the move to AM2 now?
The reason behind all this socket swapping is down to the integrated memory controller that AMD introduced with the original Athlon 64 range. At the time it was seen by some as a controversial move, because it locks the processor to a single memory technology. The payoff, however, is greater performance due to lower latency and additional performance advantages in multi-core processors. This is because it can eliminate unnecessary memory accesses that can be halted on-chip, rather than the far longer process of sending requests to the northbridge for resolution.
This enables us to shed light on the move to socket AM2. The reason is the introduction of DDR2 memory for the Athlon 64 platform. Technically, there’s no need for the shift in socket; the DDR2 lines could be happily accommodated by socket 939. To avoid confusion and people attempting to use the wrong model of Athlon, AMD has chosen to shift to the 940 pins of socket AM2.
Necessary upgrade
If that figure sounds familiar then it should be pointed out that these sockets are keyed differently to the 940 Opterons. The shift also makes sense as you will, of course, have to upgrade to a new board anyway because you need one sporting fresh DDR2 slots.
As for DDR2 support itself, at launch AM2 processors will support dual-channel DDR2-800. However, we’re told by AMD that unlike DDR1 models that were limited to a maximum speed of DDR1-400, the DDR2 controller will automatically support faster memory speeds, which will be DDR2-1066. The first samples of this memory type are just becoming available.
For testing purposes AMD sent over an AM2 motherboard with 1GB of DDR2-800 memory and the latest Athlon 64 FX62. For a while now AMD has had a good spell wearing the performance crown. While Intel is struggling switching between its outgoing P4 NetBurst architecture and new incoming Core Duo platform, AMD has been free to rule the performance desktop space. Yet monarchs usually have a shaky grasp on their thrones and the FX62 looks like it’s the last triumphant gasp for AMD’s 90nm technology that has, so far, done the company proud.
The FX62 itself is a 2.8GHz dual-core Athlon 64 with twin 1MB of L2 cache. This is a speed bump over the FX60 that ran at 2.6GHz and of course the shift to socket AM2 with DDR2. As expected, the processor simply reinforces AMD’s current grip on the performance crown, coming ever so close to be the first system to top the 300 rating in Sysmark (it actually scored 297). With a Radeon 1900XTX, 3DMark 06 hit 6,044, 3DMark 05 achieved 11,902 while Doom 3 batted along at 159.1 FPS. Media performance scaled equally well with the Windows Media Encoder test passing in two minutes dead and for 1,080p playback the average CPU usages was just 19 per cent with a peak of 40 per cent.
These results produced no surprises, but the running temperature of the FX62 is hot at 86 degrees C. This 125 watt CPU is one of the hottest processors we’ve seen and shows that to achieve faster speeds AMD will have to move to its new 65nm process.
And the DD2 results are…
Turning to memory, the Sandra 05 test put the DDR2-800 bandwidth at 7,110MB/s. When compared to 5,573MB/s for an Athlon 64 4800+ running DDR-400, this is a solid 27 per cent increase. To see how this improves performance we clocked the FX62 to 2.4GHz – the same as the Athlon 64 4800+. The result was that the FX62 still outperforms the 4800+, but only just. The FX62 scored 268 in Sysmark, 2:16 in WME and 146 in Doom 3, compared with 266, 2:24 and 140 for the 4800+, respectively. At best the DDR2 memory is offering a 6 per cent increase in speed. This is hardly awe-inspiring, but the gain is there to be had for someone who wants to sink the best part of a grand into the kit, and it proves that AMD was right to hold off on DDR2.
AM2 isn’t just about DDR2. Processors, including the FX62, that support AM2 will come with additional new features. The first is AMD’s Pacifica Virtalization. It’s not compatible with Intel’s equivalent, but it’s a technology that’ll become increasingly important at the sever level. This will also enable home users to run virtual PCs with even greater speed, so AMD has make efforts to stake its claim on this segment of the market.
Because AMD is introducing a complete range of AM2-compatible CPUs, it’s also taking the chance to categorise them into two power envelopes – either 65 watt or 35 watt – while the FX range sits in its own ridiculous 125-watt throne. While these ratings won’t affect functionality, they will help people choose the right type of CPU. So, if you want a quieter, cooler processor opt for a 35-watt unit.
The introduction of AM2 was inevitable and unfortunately the benefits of DDR2 are still slim even with DDR2-800. We’re told that it should be with us as a socket for around two years. That is, until DDR3 comes to the desktop, at which point everything will change again.
Neil Mohr
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