Athlon 64 X2 and Pentium D memory comparison.

Today, my colleague Yuriman and I, decided to do some performance comparisons on the effects of memory bandwidth on our computer systems. The evidence that is going to be presented to you is one-hundred percent repeatable and one-hundred percent verifiable. The test was to view what a 40% reduction in system memory bandwidth on each of our respective systems would do to the performance of our computers. Of course, before we did the test, we had formed the hypothesis, based off of what was learned on these forums, that the Athlon 64 X2 platform would have less of a performance hit than the Pentium D platform.

Before we begin, it must be stated that both of these machines pass dual Prime 95 for more than 24 hours, have no viruses, have no spyware, have all the latest drivers as of 4/29/06, and are free of any detectable defects that were not mentioned. To put it simply, these machines are rock solid.

The two platforms tested were as follows:

System One:

AMD Athlon 64 X2 3800+ @ 2.5Ghz
ATi Radeon X850XT @ 560/560
DFI Lanparty NF4 Ultra
2x1GB of PC4000 DDR running at the timings 3-4-3-8(250Mhz memory)
(All other system information is irrelevant)

System Two:

Intel Pentium D 820 @ 2.8Ghz
ATi Radeon X850XT @ 560/560
Intel D945PSN
2x1GB of PC5300 DDR2 running at the timings 4-4-4-13(333Mhz memory)
(All other system information is irrelevant)

The applications that were used are as follows:

UMark
Super Pi
Everest Home Edition
Pocket DivX Encoder
CPUMark
Sisoft Sandra
WinRAR

Each of these applications is of the latest version available as of 4/29/06.


The tests were run on each system first at the settings stated in the system specifications, and then a second time with the following changes:

System One; Memory clock changed to 150Mhz

System Two; Memory clock changed to 200Mhz

The resulting drop in overall system memory bandwidth is a theoretical 40%.



The format for the results will be the original configuration followed by the configuration with a 40% reduction in memory bandwidth, then showing the percentage of performance lost. For all benchmarks except those recorded by time, higher is better. Percentage loss remains the same for easier comparison between time and score.

The results are as follows:

UMark Flyby:

System One (AMD) 2622.852 -> 2250.548 -> 15.2%
System Two (Intel) 1940.389 -> 1890.542 -> 2.6%


UMark BotMatch

System One 1166.952 -> 1001.583 -> 15.2%
System Two 840.949 -> 811.129 -> 3.6%


Super Pi 1M

System One 35.782 Seconds -> 39.312 Seconds -> 9%
System Two 46.969 Seconds -> 48.735 Seconds -> 3.7%


Everest Memory Read

System One 5075MB/s -> 3641MB/s -> 29.3%
System Two 5415MB/s -> 4719MB/s -> 19.9%

Everest Memory Write

System One 2088MB/s -> 1426MB/s -> 32.8%
System Two 2225MB/s -> 1725MB/s -> 23.5%

Everest Memory Latency

System One 52.3ns -> 82.9ns -> 37%
System Two 100.6ns -> 118.3ns -> 15%


Pocket DivX Encoder

System One 9:09 -> 9:28 -> 3.4%
System Two 13:28 -> 13:39 -> 19.2%


CPUMark

System One 286 -> 270 -> 6.6%
System Two 163 -> 163 -> 0%


Sandra Memory Bandwidth

System One Int 6199MB/s -> Int 3693MB/s -> 41.5%
Float 6083MB/s -> Float 3656MB/s -> 39.9%

System Two Int 4961MB/s -> Int 4498MB/s -> 9.4%
Float 4973MB/s -> Float 4494MB/s -> 9.7%


Sandra Multimedia

System One Int 46923 it/s -> Int 47119 it/s -> 0.5%
Float 51134 it/s -> Float 50941 it/s -> 0.4%

System Two Int 31382 it/s -> Int 31364 it/s -> 0%
Float 37201 it/s -> Float 37216 it/s -> 0%


Sandra Arithmetic

System One ALU 22285 MIPS -> ALU 22244 MIPS -> 0%
Whetstone 10120 -> Whetstone 10128 -> 0%

System Two ALU 15096 MIPS -> ALU 15088 MIPS -> 0%
Whetstone 7080 MFLOPS -> Whetstone 7078 MFLOPS -> 0%


WinRAR Decompression

System One 31 Seconds -> 31 Seconds -> 0%
System Two 46 Seconds -> 47 Seconds -> 2.2%


WinRAR Compression

System One 206 Seconds -> 263 Seconds -> 22.7%
System Two 549 Seconds -> 568 Seconds -> 3.4%


It is first necessary to understand that this is not a comparison of the performance of these two systems. It is a comparison of processors, their memory architectures, and consequently, their respective relations to the overall performance of the system.

It is supposedly common knowledge that AMD K8 architectures are more efficient than Netburst processors when it comes to memory bandwidth efficiency. These tests do not prove it true or false. However, what these tests do show is that AMD processors are capable of benefiting from increased memory bandwidth just as much, if not more so, than Intel processors. The tests show with little variance, that the AMD processor has a larger difference in performance when memory bandwidth is altered.

As a consequence of some non standard configuration settings, we must bring forth the platforms themselves into consideration. The Intel system is an entry level dual core processor, consequently, the memory bandwidth requirements may be less than that of a higher end processor. By contrast, the AMD processor is at a clock speed that puts it at, or near the highest end of high performing processors; as a result, the memory bandwidth requirements may be greater than average. Nonetheless, the results shown by these tests should not be ignored. The fact that there is a performance difference between the system when the memory speed is changed, shows that at least dual core AMD processors are capable of benefiting from even faster memory.

The results lead us to believe that AM2 may possibly bring a greater than expected performance increase to AMD processors in at least some scenarios. As we ponder the aforementioned, the question of whether or not the extra bandwidth that DDR2 provides can offset the increase in latency. Perhaps later, we shall do extensive testing in the areas of memory timings on both DDR and DDR2 platforms.

Discuss.

I let him do all of the typing. I cannot count how many times I have done interesting tests, but did not share the results due to my dislike of typing large documents.

interesting results, nice work. i wasnt aware that memory did have a effect on memory speed.
Indeed the persian prince as spoken . and yes mr. yuriman i also dislike typing of large documents.

I think this should have been posted in the front page discussions, but wth

We need low latency DDR2 for AM2!

dan

We would liked to have overclocked the Pentium-D, but due to motherboard limitations, we were forced to run it at stock. The results would probably have been different, perhaps by a large amount, had we raised the FSB to 333, but since we can't, I again state that we are not comparing the two systems directly, but showing the effects on each system. The guys at Anandtech seem to have a hard time understanding this,

Also, since there is no "true" 1:1 on an Athlon64, we might as well run it at 200MHz with a 5:4 divider. There is no easy way of direct comparison. This just shows how a higher-clocked Athlon64 will react.

I just remembered something which should have made it into the original post. Most of the tests we ran were only single-threaded, so in many cases, the second core was not used much, if at all. The drop would likely be much larger in multi-threaded applications.

If I take this along with the claimed results on the conroe (40%), toss in an off the cuff remark such as "it scales with an fx but clocks higher" (yonah) and it does look interesting. Interesting test, very interesting indeed.

Good solid test. It doesnt really show anything we didnt already know though ....