AMD Athlon 64 FX-51

AMD and Intel have been going slow on processor releases of late since the current crop of processors are powerful enough for most purposes. However, it would be a mistake to think that both these companies are resting on their laurels, and are not doing much research and development. The hardware community has been buzzing with the news of 64-bit processor releases–the Itanium from Intel and Opteron from AMD. Both these processors are meant for servers and high-end workstations, and are more or less out of the reach of the common man. Which of course, brings us to our review of the month — the Athlon 64 FX-51, the highest end desktop processor from AMD till date. 

AMD and Intel have taken very different routes to their respective 64-bit goals. Intel has developed a whole new architecture called IA-64, which is not based on traditional x86 at all. It is able to run old 32-bit programs, but only through emulation that considerably reduces the performance. AMD, on the other hand, has basically extended x86 to have 64-bit support. The move to 64-bit has the biggest effect on the amount of memory that is addressable by the CPU. With 32-bit, high-end systems were pushing the 4 GB limit that is inherent to the architecture. 64-bit hikes up this limit to many terabytes.

Perhaps one of the biggest changes is the inclusion of a memory controller on the processor itself. This contributes heavily to the large number of pins (940), but allows for a reduction in memory latency. Of course, AMD has also tried to ensure that the CPU does not have to access the main memory too often by giving it 128 KB L1, and 1 MB of L2 cache. The branch prediction logic has also been improved upon, and a larger TLB (Translation Look-Aside buffers) with reduced latencies has been included. 

Our test system came equipped with Nvidia’s latest chipset based board–the nForce3 Pro 150. This plus the remaining hardware was something any die-hard gamer or enthusiast would give an arm and a leg for. Two Western Digital Raptor 10K RPM drives were put in RAID and had WinXP, plus another WD400 parallel ATA played host to a preview 64-bit edition of WinXP. Video was driven by GeForce4 FX 5900 with 256MB DDR, and two 512 MB CL2.5 DDR ECC modules served the dual memory channels. We had to get rid of some of this hardware for comparison purposes, but have still included the results that you can expect, if you go for an absolutely top-end system. 

One of Itanium’s biggest weaknesses has been in 32-bit operation. However, thanks to AMD’s different approach, such problems are almost non-existent on the Opteron/Athlon64. Our processor ran at 2.2 GHz, and we pitted it against Intel’s P4 3.2 GHz in 32-bit operation. The P4 was running on a 865-chipset based motherboard, which is slightly slower compared to the 875, but the difference is quite low (~5%). Giving a verdict on 64-bit operation is still very difficult, as Microsoft still hasn’t released the 64-bit version of Windows XP, but is expected to do so soon. Hence, we used some special benchmarks provided by AMD on a preview 64-bit WinXP to see the difference in performance. 

There has been a lot of talk about the Athlon64, and how it would be a feather in AMD’s cap. Clock speed wise, this is not the fastest CPU from AMD’s stable, but with the new architecture and platform, we were expecting this CPU to perform quite well, and it sure lived up to our expectations. Even though the Athlon64 will be marketed as a 64-bit processor, its performance in 32-bit apps is nothing to scoff at. It easily beat all its predecessors from AMD, and even managed to give the P4 3.2 a thrashing in almost all benchmarks we used.

The Athlon64 FX galloped away with the crown in Business and Content Creation Winstone with a lead of almost 30% and 25% respectively compared to the P4. 3Dmark2001 and QuakeIII Arena also saw the Athlon64 leading by small margins. In our two media encoding benchmarks, the P4 managed to edge out a lead in MP3 encoding, but faltered in DivX encoding.

Overall, a very healthy boost in performance for AMD’s chips.

Coming to 64-bit performance, we were unable to run Content Creation and Business Winstone as they simply wouldn’t install on our 64-bit WinXP. This does not mean that 32-bit apps will not work in a 64-bit OS, since Microsoft has already publicized its WOW64 (Windows on Windows) technology that would aid in this. Running our other native 32-bit benchmarks in 64-bit WinXP gave either the same results, or slightly lower ones. However, there is a big boost to be had by writing applications for 64-bit operation, proof of which lay in the tremendous improvements we saw in the benchmarks provided by AMD. These benchmarks were basically tests that would test the speed of some cryptographic functions in algorithms like RC4, DES etc. Almost all of them show huge increases in speed in 64-bit mode. 

S N   A   P   S   H O   T Price : ~$733 Key specs : AMD64 technology with 32-bit support, 940 pins, integrated DDR memory controller, hypertransport technology, 128 KB L1, 1 MB L2 cache, 3DNow! + SSE2 Contact : AMD, Bangalore. Tel : 51123540/41  E-mail : amd@surfgold.com

The bottomline: The Athlon64 FX is here with a big bang, and is sure to cause a few ripples in the CPU scene. Its performance is top-notch, with the added bonus of 64-bit operation. As more and more developers shift to 64-bit platforms, the Athlon64 will be there to support it, and till then will give little reason to complain in 32-bit mode. We expect to see other variants of the Athlon64 soon enough, one of which will even be available for mobile platforms. As of now, this is the best processor that money can buy for people who indulge in CPU crushing tasks like heavy gaming, digital video content creation and science and engineering packages.

Anuj Jain