Bandwidth Efficiency at 35%?

Hi all,

I just bought a new computer system that has a:
P4 2.8c Ghz CPU FSB800
ASUS P4R800-VM Motherboard
512 Hynix PC3200 DDR SDRAM
Built in ATI Radeon 9200 Video w/ 128 onboard memory
Case w/300 Power Supply

I downloaded SiSoftware SANDRA 2004 to test the system to see how is
it and it seems pretty good except for the memory benchmark.

It gave the memory Bandwidth Effieciency as 34%-35%.

This is what SANDRA'S website had to say about it.

"Q: Why do some systems show close to 95% bandwidth efficiency and
others less than 80%?
A: While the code for all CPUs is heavily optimised, the effciency
depends on chipset performance and memory settings. Only the most
aggressive settings may yield > 80% efficiency, thus anything higher
is a bonus."

http://www.sisoftware.net/index.html?dir=qa&location=ben_mem&langx=en&a=

The reason why I'm asking this is because I'm wondering whether I have
a faulty ram and should get it replaced? 35% effiency seems awfully
low.

However, SiSoftware SANDRA recommended this solution.

"Warning W5400 - Low memory bandwidth efficiency (advanced test).
Generally this means a setting is incorrect or set too "safe"
resulting in too low performance.
Fix: Check memory timings (reduce them) or check other chipset or
memory speed settings."

The problem is, is that I don't see anywhere in the bios or anywhere
else in the computer that can adjust the memory speed/timings.

The only thing I can find in the bios is "DRAM CAS Select: Slow/Fast".
It doesn't matter which one I choose, the same benchmark is shown.

Here is the whole report in case you wanted to read it.

~~~~~~~~~~~~~~~~~~~~~~
SiSoftware Sandra

Int Buffered iSSE2 (Integer STREAM) Results Breakdown
Assignment : 2190MB/s
Scaling : 2196MB/s
Addition : 2211MB/s
Triad : 2208MB/s
Data Item Size : 16-bytes
Buffering Used : Yes
Offset Displacement Used : Yes
Bandwidth Efficiency : 34% (estimated)

Float Buffered iSSE2 (Float STREAM) Results Breakdown
Assignment : 2200MB/s
Scaling : 2205MB/s
Addition : 2217MB/s
Triad : 2215MB/s
Data Item Size : 16-bytes
Buffering Used : Yes
Offset Displacement Used : Yes
Bandwidth Efficiency : 35% (estimated)

Test Status
Memory Used by Test : 191MB
NUMA Support : No
SMP Test : No
Total Test Threads : 1
SMT Test : Yes
Number of Test SMT (per CPU) : 2
Dynamic MP/MT Load Balance : No
Processor Affinity : No

Chipset 1
Model : ASUSTeK Computer Inc ??? (5833)
Front Side Bus Speed : 4x 200MHz (800MHz data rate)
Width : 64-bit
Maximum Bus Bandwidth : 6400MB/s (estimated)

Logical/Chipset 1 Memory Banks

Features
MMX Technology : Yes
SSE Technology : Yes
SSE2 Technology : Yes
SSE3 Technology : No
HTT - Hyper-Threading Technology : Yes

~~~~~~~~~~~~~~~~~~~~~

Please let me know if you need any more info. If anyone has any ideas
as to how I can increase my memory settings/timings, that'd be greatly
appreciated. If not, I'm assuming I should have the Ram replaced.

Hope to hear from anyone soon,

Ranma

p.s. Maybe I should use a different Memory Benchmark program?

 

Hello!
I have the same issue and I really want to know what's wrong.
I have the same configuration of the hardware (P4 2.8c Ghz CPU FSB800,
ASUS P4R800-VM Motherboard, 1x512MB DDR PC3200), so results of benchmarks
must be the same, but arent really - my memory bandwidth is about 2077
MB/s. I think that the only component that can make this difference is
RAM...or something around it(maybe the shared part of RAM can also affect
- so that can be the reason of this issue...I'll do some tests to find
this out).
When we are talking about bandwidth efficiency note that the peak
bandtwidth with one channel (1x256,1x512,...) is max 3200 MB/s and with
two channels (2x256,2x512,...) is max 6400 MB/s. So i think that sisoft
sandra results are 35% of 6400 MB/s ...this carry your 2190MB/s
(and mine 2077MB/s), in reality this mean that your bandwidth efficiency
is 68% (mine 64%). But numbers stil doesn't match - more than 30% is lost.
If we assume that in our best case there will be 95% efficency, there are
still around 25% lost. In normal case there must be a bandtwidth from
2700MB/s to 3100MB/s.

Where are the others 25% ??????????
Anyone know that?????????

...now I go to check if the shared graphics memory affect that...i will
post there what I'll find out...

Anyone who know something about that, help us. Please!

 

I stopped using SiSoft's Sandra years ago, so I won't comment on that
package. I currently use Everest (see www.lavalys.com) for such stuff.
But Everest and Sandra share a common constraint, in that they both
attempt to measure bandwidth from within the OS -- and the results are
sometimes heavily influenced by the OS *and* by the other apps with
which the benchmark app shares the OS's resources. So, for best
results, before running any such benchmark under an OS, give the system
a fresh boot and run as close to standalone as possible.

As an example, I just ran the Everest memory read benchmark twice: with
a couple of low-priority CPU-eating apps running, Everest reported
4029 MB/s; with those CPU-eaters stopped, Everest reported 5205 MB/s.