Review: AMD Duron 950MHz processor

AMD has been a fierce competitor in the low-end market since the release of its first K6 CPU. Since then, it has fought Intel on all fronts, high and low. With its position in the high-end market fairly secure, AMD once again set its sight on its old enemy, the Intel Celeron. In order to compete with Intel on the same level, it released a new Athlon-based low-end CPU, the Duron, with speeds now reaching up to 950MHz at low prices, giving it a chance to be an ideal Linux CPU.
The chip

The Intel Celeron is essentially a Pentium III-Coppermine with half of the L2 cache disabled, running with a 66MHz front side bus speed. This is good for Intel because if a chip has problems with the L2 cache Intel can disable half of the cache and repackage the chip as a Celeron. However, because of the fact Intel just disabled half of the L2 cache on a Pentium III instead of redesigning the core, the cache goes from being eight-way set associative to four-way. The set associative cache is used to make the L2 cache more efficient, so the CPU spends less time waiting for data from system RAM. By cutting it in half for the L2 cache on the Celeron, Intel cut the cache hit rate. With a low hit rate, it means more time wasted finding data in system RAM.

The Duron, however, is very much its own CPU. Designed from the ground up as a low-end processor, it is not “crippled” like a Celeron. It has half the L2 cache of a Celeron, 64KB, but features 128KB of L1 cache compared to 32KB on a Celeron. The L2 cache on the Duron is 16-way set associative, allowing it to have a high hit-rate for the L2 cache. This proves crucial, because it allows the Duron to outperform a comparably clocked Celeron by large amounts.

The chip itself is similar to the Thunderbird CPUs, because it uses the same “flipchip” configuration (with the CPU core on the top) and the same interface — Socket A. The Duron, however, has a much smaller core than the Thunderbird, using 12 million fewer transistors (25 million on the Duron, 37 million on the Thunderbird), thanks to the reduction of the amount of cache on the chip. This greatly decreases the heat produced by the CPU, which is always good for a CPU targeted toward lower-end machines, which tend not to be as spacious and well cooled as machines on the higher end.

Performance
System Specifications

AMD Duron 950MHz

256 Megs DDR PC2100 SDRAM from Crucial.com

Western Digital 7200 RPM 10.2 Gig Hard Drive

3Com 3C905TX-C 10/100 NIC (PCI)

300-watt AMD-approved ATX Power Supply
Abit Siluro GeForce 2 MX400 64MB AGP

Mandrake 8.0 with Kernel 2.4.3

For performance comparison purposes, similarly configured systems are used, where only the memory type (PC133), the processor type and the motherboard are different.

Kernel compiles

To test both the board’s stability and speed, I ran three sets of Linux kernel compiles on this board. One is a normal, “uniprocessor” make, or make -j1, which is the default. This uses one process, and does not always maximize system usage. I then did make -j2, which spawns a second process. The last test I run is with make -j3, spawning two extra processes. I do this for several reasons — to find the “sweet spot” for the board/CPU, as well as to stress the system as much as possible when trying to rate its stability. Also, the kernel is extremely useful as a measure of integer performance. In order to compile the kernel, I untarred kernel 2.4.6, ran ‘make config’ and used the default values (In other words, I held down the ‘Enter’ key)

Here we see results that aren’t really a surprise — the Duron is slower than the other CPUs here, with the exception of the old Athlon-Classic 750. However, it certainly holds its own in compiling — especially when you consider the 950 is available for half the cost of most of these CPUs, and that the Durons just just below this are considerably cheaper than the 950, with similar performance. Certainly, if you are a big-time coder, it would be worth it to get a faster CPU, but for those who only compile once in a while, or not at all, a Duron should be an excellent option.

POVRay Benchmarks

POVRay is a multi-platform raytracing program. It is a floating point intensive task and serves well to help measure the floating point performance of a CPU. For more information on this benchmark, head to the official POVBENCH homepage. The command to run for this benchmark, once you obtain POVRay, is povray -i skyvase.pov +v1 +ft -x +mb25 +a0.300 +j1.000 +r3 -q9 -w640 -H480 -S1 -E480 -k0.000 -mv2.0 +b1000 from the command prompt. Results are in seconds.

POVRay does well with the Duron, with scoring that is in line with Athlons of similar clock. On-screen rendering would require more of the CPU’s other facilities, such as L2 cache, but rendering to file such as what POVRay does depends a lot more on the FPU power of the CPU than anything else, and the Duron Floating Point Unit is just as good as the Athlons.

Here we find the Duron is an excellent gaming CPU — most new games are more video-card intensive than CPU intensive. The work of rendering the game is loaded onto the 3D processor while background tasks such as AI and network communications are handled by the CPU. As this progression continues, it depends less what CPU you run and more what video card you use. If you put a GeForce3 into this system, you could very well find it to have similar top speeds to the highest-end Athlon, at an extremely reduced cost.

Conclusions
For those looking for a value processor, you cannot beat the Duron line of CPUs. The 950MHz model is plagued by a problem that all top-of-the-line CPUs face, increased cost. The Duron 950 is $24 dollars more on Pricewatch than its 900MHz version, yet the chips will score almost identically in benchmarks. Because most users looking at Durons want value, this should be taken into account.

However, the Duron performs as well it was intended to, and perhaps better, in some tests performing similar to its more expensive sibling, the Athlon. For those looking for an upgrade from older systems, such as K6 or lower-MHz Pentium II/III based systems, the Duron allows you a quick upgrade path. For $24, you can pick up a Duron 700MHz CPU, and a few months down the road pick up a 1.33 or 1.4 GHz Athlon as they drop in price. Duron certainly fits in the class of a lot of value for a little cost. The Duron 950MHz is available on Pricewatch for $76, and the 900 for $52.