Put an Athlon 64 X2 on the bench next to a regular Athlon 64 and you won't be able to tell the two processors apart as all of the changes are internal. As with the dual-core Opteron you should be able to upgrade your existing Athlon 64 PC after a BIOS update - there's no need to change your motherboard. Indeed, with the 110W power rating we would hope that you would be able to continue using your existing heatsink/fan unit.

We built the AMD hardware into a test system by adding an Areca 1220 PCI Express RAID card and four Western Digital Raptor WD740 hard drives in a RAID 5 array, along with an Antec True550P EPS12V 550W power supply that we had on the test bench and which happened to be exactly the model that AMD recommends. We let the side down a bit by installing an Asus N6600GT graphics card as that's what we happened to have to hand. Yes, a GeForce 6800 Ultra or Radeon X850 PE would have been nice but as you'll see it wouldn't have affected our test results one little bit. So that we at least looked like we were trying we ran the Asus N6600GT at 550MHz core and 1100MHz memory on Detonator 71.84 drivers.

We started by running SYSmark 2004 on the X2 4800+, and we immediately hit a problem. We were using Windows XP Pro Service Pack 2, and the Office part of SYSmark wouldn't run as the No Execute protection kept kicking in. This occurred a number of times until we disabled both of the integrated LANs and installed an Intel Pro/100 NIC and then switched from Nvidia's firewall to the Windows firewall. This is particularly odd as you inherently run SYSmark 2004 with networking disabled so you wouldn't have thought that it would much matter what the settings were but there we have it.

Once we'd cured the problem, the X2 4800+ pumped out a startling score of 281 in SYSmark 2004, while the results in 3DMark05 and Doom 3 were much as you would expect.

We removed the X2 4800+ and replaced it with an Athlon 64 FX-53 which runs at the same 2.4GHz and also has 1MB of L2 cache, so we were able to carry out a direct back-to-back comparison between single-core and dual-core processors and the results were telling. There was no change at all in 3DMark05 and Doom 3, but the SYSmark 2004 score dropped from 281 to 214 marks. Most of the change was in the Internet Content Creation part of the test where the software runs scripts in Discreet 3D Studio Max, Adobe Photoshop, Macromedia Dreamweaver and the like.