Athlon 64 Memory: Rewriting the Rules

Performance Test Configuration

The first tests with the new Athlon 64 test bed were in the recent OCZ PC3700 Gold Rev. 3 review. In this round, we extend the Athlon 64 memory tests to some of the fastest memory that we have tested and the newest memory in our labs. Since we have found DDR memory to perform very differently on the memory controller with Athlon 64 chips, we will be including Athlon 64 benchmarks in all future memory reviews.

The A64 test bed includes components that have been proven in Socket 939 Athlon 64 benchmarking, such as the Gold Editors Choice MSI K8N Neo2, the completely unlocked Socket 939 FX53, and the OCZ Power Stream 520 Power Supply. Since the Athlon 64 tests represent a new series of DDR testing, we have chosen the current generation nVidia 6800 Ultra video card for benchmarking. We have found the 6800 Ultra to be a particularly good match to nVidia nForce3 Ultra motherboards.

All other basic test conditions attempted to mirror those used in our earlier Intel memory reviews. However, test results are not directly comparable to tests performed on the Intel test bed.

AMD nForce3 Ultra Performance Test Configuration
Processor(s):	AMD FX53 Athlon 64 (2.4GHz, Socket 939, Dual Channel, 1000HT)
RAM:	2 X 512MB Crucial Ballistix (DS) 2 X 512MB Geil PC3200 Ultra X (DS) 2 X 512MB G. Skill TCCD (DS) 2 X 512MB OCZ PC3200 Platinum Rev 2 (DS) 2 X 512MB OCZ PC3700 Gold Rev 3 (DS) 2 X 512MB PQI 3200 Turbo (DS)
Hard Drives	Seagate 120GB PATA (IDE) 7200RPM 8MB Cache
PCI/AGP Speed	Fixed at 33/66
Bus Master Drivers:	nVidia nForce Platform Driver 4.24 (5-10-2004)
Video Card(s):	nVidia 6800 Ultra 256MB, 256MB aperture, 1024x768x32
Video Drivers:	nVidia Forceware 61.77
Power Supply:	OCZ Power Stream 520W
Operating System(s):	Windows XP Professional SP1
Motherboards:	MSI K8N Neo2

We have found the fastest performance on AMD Athlon 64 chipsets (nForce3, VIA K8T800 PRO) to be achieved at Cycle Time or tRAS of 10. Athlon 64 platform benchmarks were, therefore, run with the tRAS timing of 10 for all A64 benchmarks.

Test Settings

The FX53 is completely unlocked, something not currently available with Intel processors. This allowed a different approach to memory testing, which truly measures performance differences in memory speed alone. All tests were run with CPU speed as close to the specified 2.4GHz of the FX53 as possible, with CPU speed/Memory Speed increased at lower multipliers to achieve 2.4Ghz. This approach allows the true measurement of the impact of higher memory speed and timings on performance, since CPU speed is fixed, removing CPU speed as a factor in memory performance.

The following settings were tested with the six memories on the Athlon 64 test bed:

1. 12x200/DDR400 - the highest stock memory speed supported on K8T800/nF3/SiS755 motherboards.
2. 11x218/DDR436 - a ratio near the standard DDR433 speed.
3. 10x240/DDR480 - a ratio near the standard rating of DDR466.
4. 9x267/DDR533 - a standard memory speed used in testing other high-speed memory.
5. Highest Memory Speed - the highest memory speed that we could achieve regardless of the multiplier. This setting was generally achieved at a 2T command rate and performance is often poorer than slower memory timings at a 1T Command Rate.
6. Highest Performance - the highest memory performance settings that we could achieve. This setting is normally the highest stable speed using a 1T Command Rate.

A couple of the memories tested here were able to run at an incredible 8x300/DDR600 speed. This is the next ratio multiple for 2.4GHz speed and will be added to future memory benchmarks as more memory is able to reach this performance level.

Command Rate is not normally a factor in Intel 478 tests, but it is a major concern in Athlon 64 performance. A Command Rate of 1T is considerably faster on Athlon 64 than a 2T Command Rate. For this reason, we had added the Command Rate to the timings and voltage reported for each memory speed setting.

We ran our standard suite of memory performance benchmarks - Quake 3, Super Pi 2M, and Sandra 2004 UnBuffered. Since the results for Athlon 64 tests are new, we are now including Sandra Buffered (Standard) test results as well as Sandra UnBuffered test results. Return to Castle Wolfenstein-Enemy Territory has also been added as a standard memory benchmark.