Memory Bandwidth problems :-(

[Rajveer]

Hi everyone, my name is Rajveer and I'm new to these forums. I chose tweaktown to share my problem with as its usually full of people who know what they're talkin about!

After slugging it out with an old Dell for the past 5 years, I thought I'd treat myself to a totally new computer a month ago, so I went out and got myself:

Coolermaster Wave Master Case
Abit AW8-MAX motherboard
LGA775 Pentium 4 650 3.4GHz
Corsair XMS2 1GB DDR2 XMS2-8000UL Low Latency TwinX (2x512MB) (running at DDR2-667 5-4-4-9)
Maxtor 300GB SATAII hard drive
Leadtek Geforce 7800GTX 256MB
My old DVD and CD-RW drive from Dell...gotta save some money hehe
Along with my old ThermalTake Butterfly 480W (which I REALLY need to change!)

I have a few problems with my PC, random crashes during idle and loading maps in BF2 (which I'm putting down to my PSU), and slow memory.

When I run the memory benchmark in SiSoftware Sandra (latest version), I get around 4977MB/s for "RAM Bandwidth Int Buff'd iSSE2" with 79% efficiency: however for "RAM Bandwidth Float Buff'd iSSE2" I get 1775MB/s with 28% efficiency! Why I get this I don't know, I'm pretty sure I have everything setup correctly, and the fact that I get a much higher integer bandwidth confirms this, doesn't it? I'm told in Sandra I should increase my FSB which is currently at 200Mhz, but I shouldn't need to do this for my memory to work at stock speeds! Please help!

Thanks for your time!

[Rajveer]

Re: Memory Bandwidth problems :-(

bump! somebody must be able to help me or know something about this problem, no?

[Yawgm0th]

Re: Memory Bandwidth problems :-(

I have no idea if that bandwidth score is any good, and it reallly shouldn't matter. Unless you're getting poor performance in any actual programs, don't worry about it.

As for your instability, it's only the PSU if it doesn't have a 24-pin connector. The use of a 20-pin connector can cause the kind of instability you have, but a 480W TT Butterfly should have no problems handling that system at stock speeds.

[Rajveer]

Re: Memory Bandwidth problems :-(

Thanks for your reply! thought it was the PSU, you confirmed it as its only 20-pin. Just ordered a new psu.

As for the bandwidth, by what I can gather the majority of healthy systems should get memory bandwidths for each test to be at an acceptable efficiency of over 70%, if not more, and both results should be very close together. I just got a bit worried since one result shows that my bandwidth is fine, and the other is waaaaay different, with such a large difference that I have never seen before.

I do seem to be getting poor performance in programs, a good example is BF2 where it does jerk alot when I haven't been in a certain area for some time. Some people put it down to not having more than 1GB of memory though. I'm still pretty worried about the bandwidth problems since I've never come across this before, the bandwidth only seems to go down when using floating point data, could this be a problem with my processor processing floating point numbers?

Cheers for your time!

[Yawgm0th]

Re: Memory Bandwidth problems :-(

I haven't worked with DDR2 or even studied it much (see no reason to) so I don't really know there. Though those latencies look pretty high, regardless of the speed. Maybe you can mess around with those some.

IMO 1GB is plenty for BF2, but if you have too many programs running it will be as if you had less.

Out of curiousity, what made you decide to go with an LGA775 system with DDR2?

[Rajveer]

Re: Memory Bandwidth problems :-(

The rated latencies are 5-4-4-9 even when overclocked at 1066MHz (which the RAM supports as well as my motherboard) but I'll definately give it a try.

Only other memory-intensive application is Kaspersky Lab AVP.

I chose the LGA775 processor as I've has alot of success overclocking Pentium 4's in the past and never used an AMD, I don't like change (even though AMD are just as good a choice and more power saving). I also had a higher budget since I've never actually brought a performance PC before, so I thought why not go all the way with DDR2, in some tests and benchmarks it makes quite alot of difference...except for in my case where im getting weird results!

[Yawgm0th]

Re: Memory Bandwidth problems :-(

The rated latencies are 5-4-4-9 even when overclocked at 1066MHz (which the RAM supports as well as my motherboard) but I'll definately give it a try.

Only other memory-intensive application is Kaspersky Lab AVP.

I chose the LGA775 processor as I've has alot of success overclocking Pentium 4's in the past and never used an AMD, I don't like change (even though AMD are just as good a choice and more power saving). I also had a higher budget since I've never actually brought a performance PC before, so I thought why not go all the way with DDR2

Actually they're a much better choice as they outperform their Intel price couterparts in almost every concievable application at every price point. A higher budget would mean an AMD system all the same as a lower budget would. :) DDR2 can make a difference over DDR on an LGA775 system, but DDR on a socket 754 or 939 platform will still do better. P4s also aren't as good for overclocking anymore because they come in higher clockspeeds and don't really go any further, so overclockers are quite often paying more for the same when compared with the old socket 478 P4s.

But nevermind that, because Intel or not that system's no slouch and you sohuld't be having problems. Try running the RAM at the stock speed (as opposed to overclocked or the rated speed) with lowered latencies. Also try the reverse, with the RAM overclocked but latencies increased, if necessary. It could just be that the RAM is at a particularly bad setting.

Also, try turning that AV off. Antivirus can be a huge problem for gaming. I can run BF2 on 768MB of RAM as if it were 1GB, but I never have AV on, and I have done tons of tweaking with services and the Windows UI in order to make the system use less memory.

[Rajveer]

Re: Memory Bandwidth problems :-(

Thank you very much for your time and effort! From what you've said, when I get another system in years to come it may well be designed around an AMD processor, change can also be good!

At the moment my RAM is at the standard clock speed of DDR2-667, and trying to increase the clock did not solve the problem: it increased both test results but the difference was still the same, except with improved results. Lowering the latencies to the rated ones decreased the difference a fair bit but increasing the lower test result but the difference is still quite large andI'm not sure whether I should lower them past their rated latencies? If you think it should not be a problem, and although you haven't played around with DDR2 yourself, what latencies would you recommend I try testing?

[amd_man2005]

Re: Memory Bandwidth problems :-(

It will not hurt to run lower than rated latencies, if it will remain stable. There is a ris kof instability when running below rated latencies and/or over rated speeds.

[Rajveer]

Re: Memory Bandwidth problems :-(

Cheers amd_man, I'm definately going to give it a shot when my newPSU is delivered so that I don't confuse any memory crashes with power crashes. I'm pretty new to overclocking memory, so how would I go about it? What would I adjust first out of the 4 variables and apart from tRP and tRCD being the same, are there any other proportions between the variables that I have to keep?

Sorry for asking alot, but I really am new to overclocking and how safe it is!