Memory Stress Testing

Optimum tRAS

In past reviews of AMD motherboards, memory bandwidth tests established that a tRAS of 6 was optimal for the nForce4 chipset, a tRAS of 10 was best for the nForce3 chipset and a tRAS setting of 11 or 12 was generally best for nForce2. Tests with Intel chipsets in the past have generally shown the lowest tRAS setting to provide the best bandwidth with Intel chipsets.

Since this was the first memory stress test of a production 955X board, tRAS timings were first tested with memtest86, a free diagnostic program with its own boot OS that will boot from either a floppy disk or optical disk. Bandwidth was measured from tRas 4 to tRAS 15 at the specified DDR2-667 to determine the best tRAS setting. Since Intel recommends 5-5-5-15 timings with DDR2-667, we wanted to establish recommended timings with lower latency memory from Corsair and OCZ.

 Memtest86 Bandwidth
Asus P5DW2 at DDR2-667
4 tRAS 3443
5 tRAS 3443
6 tRAS 3443
7 tRAS 3443
8 tRAS 3443
9 tRAS 3443
10 tRAS 3443
11 tRAS 3443
12 tRAS 3360
13 tRAS 3360
14 tRAS 3360
15 tRAS 2184

The best bandwidth was achieved with this combination of 955x and Pentium 560 in the 4 to 11 range. Since, historically, Intel chipsets have performed best at the lowest tRAS setting, we used a tRAS of 4 for memory tests. Any value from 4 to 11 should provide similar bandwidth.

Since memory was also tested at DDR2-800, we ran a similar set of tRAS timings at DDR2-800. At that speed, tRAS bandwidth was the same from tRAS 4 to tRAS13, so we tested with tRAS 4 for all DDR2-800 tests.

Memory Stress Tests

Memory stress tests look at the ability of the Asus P5WD2 Premium to operate at the officially supported memory frequency (667MHz DDR2), at the best performing memory timings that Corsair/OCZ PC2-5400 will support. Memory stress testing was conducted by running DDR2 at 667MHz (stock 3:5 ratio) with 2 DIMM slots operating in Dual-Channel mode.

Stable DDR667 Timings - 2 DIMMs
(2/4 DIMMs - 1 Dual-Channel Bank)
Clock Speed: 200MHz (800FSB)
Timing Mode: 3:5 (200:333 - Default)
CAS Latency: 4.0
Bank Interleave: Auto
RAS to CAS Delay: 2
RAS Precharge: 2
Cycle Time (tRAS): 4
Command Rate: NA

The Asus P5WD2 Premium was completely stable with 2 DDR2 modules in Dual-Channel at the settings of 4-2-2-4 at 1.9V.

Filling all four available memory slots is more strenuous on the memory subsystem than testing 2 DDR2 modules on a motherboard.

Stable DDR667 Timings - 4 DIMMs
(4/4 DIMMs - 2 Dual-Channel Banks)
Clock Speed: 200MHz (800FSB)
Timing Mode: 3:5 (200:333 - Default)
CAS Latency: 4.0
Bank Interleave: Auto
RAS to CAS Delay: 3
RAS Precharge: 2
Precharge Delay: 4
Command Rate: NA

4 DDR2 DIMMs were just as stable as 2 DIMMs on the new Asus 955x. We needed slightly slower 4-3-2-4 timings at DDR2-667 when using 4 DDR2 DIMMs at 1.9V. But at 2.0V, the 4 DDR2 dimms ran with complete stability at the same 4-2-2-4 timings that worked with 2 DIMMs. This is a remarkable improvement over the performance that we saw with 4 DDR2 DIMMs on the 925X. Considering the compromises that the AMD Athlon 64 has required with 4 DIMMs, Intel and Asus have done an outstanding job in equipping the 955X with the ability to run 4 DIMMs without much of a compromise.

Since both Corsair and OCZ had submitted new DDR2-667 DIMMs tweaked for best performance and low-latency in the latest DDR2 platforms, these were the only 2 pairs of DIMMs that we had for 4-DIMM testing on this new 955x board. We used a pair of Corsair and a pair of OCZ and these unmatched pairs performed fine at the same timings that worked with 2 DIMMs. Both Corsair and OCZ are based on Micron DDR2 chips, but the SPDs, bandwidth, and timings did differ in our tests of each pair, indicating that they are similar, but not identical in performance.

Asus P5WD2 Premium: Overclocking Corsair and Asus Reach DDR2-1066


View All Comments

  • chawkfan2002 - Thursday, June 02, 2005 - link

    In reading your article you indicate the “Corsair CM2X512A-5400UL could reach DDR2-1066” I am trying to determine how the memory speed is actually DDR2-1066? Your illustration indicates the FSB at 1068MHz (1066MHz) do you have any screenshot that shows the memory speed at 1066MHz? If the FSB is at 1066MHz then the memory bus is only at 534MHz (FSB 1066/4=266 actual speed… Memory bus 266x2=533 Double Data Rate) I have tried the FSB at 266 and manually changed the memory speed to DDR2-800, Memtest+ still shows actual speed at 534MHz

    Any information you can provide on how to achieve the 1066MHz actual memory speed will be most graciously accepted.
  • Makyla - Friday, May 20, 2005 - link

    pwned Reply
  • ElFenix - Monday, May 16, 2005 - link

    just because a lot of people got it wrong doesn't mean it's right. the first definition is the only proper one. that is like saying that because it is popular, on the internet, to say "he should of done that" means that 'of' is a proper substitute for 'have.'

    as for heat sink, much of that is the same. i suggest you take a look here:
  • ElFenix - Monday, May 16, 2005 - link

    ""a fan doesn't actually cool anything, it just pushes air around"

    Try disabling the fans in your rig and A/C, take temp readings before and after and get back with us. Moving same temp to same temp isn't cooling. Moving cooler air (or water or other) to something that is hotter (chip, compressor, radiator, etc) most definitely actively cools it."

    no, the conducting of heat from the radiator to the air through natural processes cools it. an air conditioner actually moves the heat against the temperature gradient. a fan cannot do that. a fan, again, isn't actually cooling anything. just because there is a moving part moving the air at a faster than natural current does not mean that the cooling is active. it is not. you're still relying on the normal radiator-air interaction. now a peltier actually moves the heat. that is active cooling. a fan only passively cools.
  • Viditor - Thursday, May 12, 2005 - link

    How about this board

    SUPER H8DCE Serverboard ( OEM White Box ) for System only
    Dual AMD Opteron 200 series Processor supported-940 pin ZIF Socket
    nVIDIA nForce Pro 2200 & 2050 Chipset
    Up to16/16/32 GB of ECC Registered DDR 400/333/266 SDRAM
    nVIDIA nForce Pro 2200 & 2050 SATA II controller for 8 SATA ports
    Dual nVIDIA nForce Pro 2200 & 2050 Gigabit Ethernet
    AC'97 audio CODEC high quality 6-channel sound
    2 X PCI-Express x16 + 2 X PCI-Express x4 + 3 X 32 bit PCI

    Dual dual Opterons with SLI...
  • Darth Farter - Thursday, May 12, 2005 - link

    Wesley Fink,

    do you know at what msrp Intel puts them (955/945)?
    also for the nf4(&ati) dual core compatible boards?
  • Wesley Fink - Wednesday, May 11, 2005 - link

    #26 - As we said in the review, we were able to enable SLI on the 955x using the old, almost unavailable nVidia 66.75 drivers. However, none of our SLI-enabled games worked properly. It was our original intention to compare the SLI performance (and we have P5ND2-SLI benchmarks), but the "Semi-SLI" was not completely working. Until the P5WD2 SLI works, and works with readily available drivers, the fact there are 2 x16 slots on the Asus 955x is academic for SLI - a promise for the future. Reply
  • Capt Caveman - Wednesday, May 11, 2005 - link

    Small Win. If you go to Asus's website, they have updated it. They now list two editions of the P5WD2 Premium board and list the Wifi-TV Card as either bundled or optional. Of course, they have yet to email me back. Or offer the Wifi-TV Card.
  • niz - Wednesday, May 11, 2005 - link

    Its a shame that they didn't bother to benchmark comparative SLI performance between the two motherboards.

    I'd like to know whether the diffrerence between the PciE slot timings (x8/x8 and x16/x2-4) really makes any difference to SLI performance.
  • HardwareD00d - Wednesday, May 11, 2005 - link

    They will probably be able to reach DDR2-4096 speeds pretty soon by setting timings to 20-20-20-60 and hooking up a 9v battery to it. Reply

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