Introduction

A few months back we took a look at a couple of AMD's X2 CPU's in the form of the 4800+ and the 4400+. Both provided excellent performance in all tasks however they did come at quite a hefty price. Since publishing those articles AMD released the 3800+ which provides AMD users with all of the benefits of Dual Core computing - however at a much lower cost. Aimed to compete directly with the Pentium D 820 in terms of price and performance we were very interested to see just how well the new chip would compete with our previous Gold Award winner.

X2 3800+

For those of you who haven’t been reading up on AMD’s recent launches the basic concept of the X2 is that it is 2 of AMD's Athlon64 cores on the same processor die. These two cores share the CPU memory controller and hypertransport connections.

The 3800+ is a 90nm Silicon on Insulator Design and uses the socket 939 connector that many of you Athlon64 users will already be using. Packed into the .90nm chip are approx 154million transistors and the approximate die size is 147mm2. This means that the CPU works in most (if not all) of the existing 939 motherboards on the market, all that is required is a bios update. We tested this CPU on an ATI reference crossfire board and a DFI Nforce 4 board with a recent bios and it worked fine, we also updated the older A8V Deluxe to the most recent bios (1014) and again no problems.

You would think that with two Athlon64 cores running on the same CPU die the thermal properties would mean a huge cooler would be required - however this is not the case and any cooler which works on an FX55 will handle the X2 with ease. Previous X2’s such as the 4800+ were 110w chips however the 3800+ (and 4200+) only use 89w (max). The chip runs on voltages between 1.3v and 1.4v.

The 3800+ has 512KB of L2 cache per core (so 1mb total). This is 512k less than the 4800+ per core. L1 Cache is 128K per core split into 64K of L1 instruction and 64K of L1 data. The total L1 cache is therefore 256KB. The speed of the 3800+ is 2.0ghz and HTT spec is 1000mhz, though this is per core so the real HTT speed is 2000mhz

The usual memory support of PC1600, PC2100, PC2700 and PC3200 is present with a max data bandwidth of 6.4GB/s throughput. This combined with the 8GB/S over HTT this gives you an effective data bandwidth of 14.4GB/s.

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