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CPU Intel P4 840 D P4 820 D P4 630 P4 640 P4 650 P4 660 P4 670 AMD Athlon64 3500+ 3700+ 3800+ 4000+ X2-3800+ X2-4200+ X2-4400+ X2-4600+ X2-4800+ 1-Way Opteron Opteron 144 Opteron 146 Opteron 148 Opteron 150 Opteron 152 2-Way Opteron Opteron 240 Opteron 242 Opteron 244 Opteron 246 Opteron 248 Opteron 250 Opteron 252 2-Way Dual Core Opteron Opteron 270 Opteron 275 nVidia GF 7800GT GF 6800GT GF 6600GT ATI R X850 XT PE R X850 XT R X800 XT PE R X800 XT R X800 XL Memory Corsair Crucial Kingston Mushkin OCZ What are you shopping for?

Different Platforms, Different Latencies

Probably the biggest selling issue of the Athlon64 in its various iterations is the integrated memory controller to allow reduced latencies on the memory controller level. It is, therefore, quite interesting to see the high memory latencies on modules qualified for this particular platform. Keep in mind that if the controller latencies are lower, the memory latencies weigh in much heavier than in a standard system where the bulk of data access latencies can be attributed to the controller. What we are getting at is the fact that if there is any system to show the impact of latencies on actual system performance, the Athlon 64 FX platform is the prime candidate for doing so.

We have taken the four candidates and run them through a number of different synthetic and more real world benchmarks and the numbers are somewhat surprising, at least compared to what we have become used to in the context of conventional platforms.

Test Configuration

Verification of Settings

It is one thing to set latencies and frequencies in the BIOS, it is a totally different story altogether whether these settings are actually executed. In the past, we have often enough encountered some severe mismatches between the BIOS GUI and the actual settings as they were enabled during system initialization and the ASUS SK8N is no exception here. For example, modules with an SPD that specifies DDR333 will not run at DDR400 even if the BIOS shows it.

Over the past months, we have come to rely on CPUz as a fairly accurate utility to show not only the frequency setting but also the latencies at which the modules are running and we used it here to verify the operating parameters of every single module before we started running benchmarks and further, in between, the reasons will become obvious on the following pages.

       

Click for larger images.

Left: CPUz screenshots of the Mushkin DIMMs running at 2:3:2. Center: all four modules in this round-up were capable of running at 2.5:3:3. Right: The Kingston and the Samsung Modules are running at 3:3:3 by default. Note also that in all cases, the frequency is shown correctly as 200 MHz (clock rate which corresponds to 400 MHz data rate or PC3200 mode)

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