[OT??] HELP: Getting lousy memory throughput from Abit KD7

From: Timothy Miller (miller@techsource.com)
Date: Thu Jul 17 2003 - 16:14:29 EST

I recently bought an Abit KD7, and I'm having a few problems with it. I
hope someone can please help me with them.

According to the BIOS screen, the board model I have is
KT400-8235-6A6LYA1AC-DN. I have an Athlon XP 2800+ (barton core,
333mhz fsb) with 1 GIG of PC2700 DDR. The board has AwardBIOS.

I'm running Red Hat 9 with their latest kernel (something like 2.4.20-18).

The Corsair memory I'm using turns out to be from SpecTek, which uses
Micron silicon. I called SpecTek to get a datasheet, and they
directed me to the data sheet for Micron MT46V64M4TG-6T.

I use the following settings for memory:

CAS latency: 2.5
Bank Interleave: 4
Trp: 3T
Tras: 7T
Trcd: 3T
Drive strength and controls are all Auto
DRAM Access: 3T
Enhance DRAM Performance: Disabled
DRAM Command Rate: 1T
Write Recovery Time: 3T
tWTR: 1T

The problem that I encounter is that I seem to be getting unusually low
memory throughput. Using "memtest86", I get 665mb/sec. Using STREAM
under Linux, I get closer to 1040 mb/sec peak. Doing some searches on
google has revealed that most people get closer to their peak bandwidth,
so, I should be expecting at least 2400 from STREAM, judging from the
numbers others are getting. I know in the real world, you never get
peak, but in synthetic tests, I should not be getting half the rated

I have already tried flashing the latest BIOS but the only result was
that "Fast CPU command decode" option now causes the system to not POST
(It didn't before).

If anyone could please help me to figure out what is slowing things
down, I would appreciate it very much.

I have a feeling this isn't a Linux-related issue, but you never know.
Does STREAM report very low throughput compares to, say, SiSOFT SANDRA?
  I haven't tried SANDRA because I don't want to install Windows.

Thank you.

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This archive was generated by hypermail 2b29 : Wed Jul 23 2003 - 22:00:30 EST