tRAS and Memory Stress Testing

Memory tRAS Recommendations

In past reviews, memory bandwidth tests established that a tRAS setting of 11 or 12 was generally best for nForce2, a tRAS of 10 was optimal for the nForce3 chipset, and a tRAS of 7 was optimal for the nForce4 chipset. The recently tested ULi 1695 was best at tRAS of 10.

Since this is our first review of a new ATI chipset, 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 of OCZ PC3200 Platinum Rev. 2, based on Samsung TCCD chips, was measured from tRAS 5 to tRAS 12 to determine the best setting.
Memtest86 Bandwidth
Sapphire PURE Innovation with Athlon 64 4000+
5 tRAS 2048
6 tRAS 2092
7 tRAS 2141
8 tRAS 2141
9 tRAS 2092
10 tRAS 2048
11 tRAS 2004
12 tRAS 1922

Two things stood out in our tRAS tests. First, the Sapphire ATI exhibits the best bandwidth at a tRAS setting of 7 or 8. We decided to use 7, since it is the same as the best setting for nForce4. Second, the bandwidth numbers on the ATI were a bit higher across the tRAS tests than what we saw with the ULi 1695. This suggests ATI having better optimized memory management - at least at this stage of development.

Memory Stress Test

Our memory stress test measures the ability of the Sapphire ATI to operate at its officially supported memory frequency (400MHz DDR), at the lowest memory timings that OCZ PC3200 Platinum Rev. 2 modules will support. All DIMMs used for stress testing were 512MB double-sided (or double-bank) memory. To make sure that memory performed properly in Dual-Channel mode, memory was only tested using either one dual-channel (2 DIMMs) or 2 dual-channels (4 DIMMs).

Stable DDR400 Timings - One Dual-Channel
(2/4 DIMMs populated)
Clock Speed: 200MHz
CAS Latency: 2.0
RAS to CAS Delay: 2T
RAS Precharge: 7T
Precharge Delay: 2T
Command Rate: 1T

Using two DIMMs in Dual-Channel 128-bit mode, the memory performed in all benchmarks at the fastest 2-2-2-7 timings at default voltage, which was the only memory voltage available.

Stable DDR400 Timings - 4 DIMMs
(4/4 DIMMs populated)
Clock Speed: 200MHz
CAS Latency: 2.0
RAS to CAS Delay: 2T
RAS Precharge: 7T
Precharge Delay: 2T
Command Rate: 2T

Tests with all four DIMM slots populated on the Sapphire required a 2T Command Rate with 4 DIMMs in two dual channels. This is the pattern seen on other top-performing Socket 939 boards. The Sapphire AMD had no problem running at a 200 CPU speed setting with 4 double-sided DIMMs. Since the Athlon 64 memory controller is on the processor, there were no real surprises in the memory stress tests. The Sapphire ATI is certainly competitive with the best Socket 939 boards in memory performance.

Overclocking: Sapphire PURE Innovation Test Setup
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  • afrost - Friday, July 29, 2005 - link

    One of the big things for me is that there is only passive cooling on the motherboard without the need for crazy heatpipes etc. This is really important for those of us who want to build silent computers.

    I'v definately picking up this board from Saphire.
  • Zebo - Friday, July 29, 2005 - link

    Good point must run at lower temp than nvidia's single chipset solution which gets hot as hell when you start cranking HTT.
  • rjm55 - Friday, July 29, 2005 - link

    We mentioned several times in the article that Sapphire will launch the new board in early August. Sapphire has confirmed their plans to launch around August 5. Sapphire has asked us to pass on that you will be able to buy retail PI-A9RX480 motherboards in most markets by August 15th-20th. Price will be "competetive with nForce4".
  • Resh - Friday, July 29, 2005 - link

    Any idea on when we will see them? I'd really like to go that route, but I can't wait forever!
  • Wesley Fink - Friday, July 29, 2005 - link

    Halibut (Crossfire AMD) and Stingray (Crossfire Intel) boards are ready to go to reviewers, but there are still some decisions being made at ATI. We have also seen the prototype retail boards from Gigabyte and another manufacturer. When ATI decides whether Crossfire will be now or with R520 (just a guess at events) Crossfire will roll out quickly.
  • Resh - Friday, July 29, 2005 - link

    Thansk Wesley. I wish they would hurry up with that decision... RAM is ordered and PSU, CPU, and X800XL will be ordered this w/e, too, so they better get the motherboards out!

    If you do hear something, please share it with the rest of us.

    N
  • coomar - Friday, July 29, 2005 - link

    wow the white pcb stands out, at least the thing is packaged well
  • Dhaval00 - Friday, July 29, 2005 - link

    A week ago, AT was having fun posting such rumors... I am sure it thinks otherwise now :).

    /me feels like getting rid of all my nVIDIA hardware.
  • ukDave - Friday, July 29, 2005 - link

    Typo on Pg8, second bottom paragraph. "ATI X350XT PE" - the '3' should be an '8' me thinks.
  • Tommouse - Friday, July 29, 2005 - link

    Nice board. Still undecided on the white color though.

    I wonder if the Zalman CNPS7700-Cu will fit :|

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