Opteron 185 EXTREMELY low memory bandwidth

[Grunt76]

I realized that my opteron 185 with 2GB RAM and Radeon X1950, while certainly not a top performance PC, should give me OK FPS, certainly in the Source engine, if not in Crysis obviously.

My setup isn't OC'ed although I watercool my CPU.

Anyway, so I ran SANDRA and here is what I discovered:

Processor Arithmetic: Exactly where I should be, a couple points above the FX-60
Processor Multi-Media: Exactly where I should be, a couple points above the FX-60
Memory Bandwidth: Holy hell... About 1/3 rd of what I should get... 1890 instead of 5300 / 5400 mb/s
Memory Latency: Hmmm... Up to 256kb data size, I am on par with what I should get. Then at 1mb I am much faster than reference (34 clocks vs about 125 ref), Which makes sense, since the CPU has 1mB of L2 cache per core. Then at 4Mb I am screwed. Getting a latency of about 500 clocks on CPU1 and 620 on CPU2 compared to my reference of 140 clocks. And it stays there at 16Mb data size and 64Mb data size.
Cache and memory bench: A little bit above reference in terms of performance.

So, any idea how to tell if it's the RAM or the chipset?

Thanks!!

 

[SlowSpyder]

The only thing I can think of off the top of my head (I'm not expert) is to make sure you're in dual channel mode. CPUZ should be able to tell you.

Also, for what it's worth with my Opteron 165 @ 2.56GHz I was able to play Crysis no problem... I just didn't want to because I found the game boring. But, it was enough CPU to play it without a problem.

*edit - I also assume you're using PC3200?

 

[Grunt76]

Yeah I am using Kingston PC3200 2x1gb.

I am planning on upgrading to the Mushkin PC4000 4x1gb but if it's my NB, I'll have to get a new mobo first, no reason to spend all that money on RAM that won't give me any good.

How much do you think I can get out of an opty 185 on water with good OC'ing RAM without any kind of risk to the CPU? Sandra says my CPU is a 23/2 (B08) JH-E6 whatever that means. I don't remember the markings on the heatspreader...

OK now I got CPU-Z going and here is what it says:

Type: DDR Channels #: Dual
Size: 2048MBytes

Timings...
DRAM Frequency 100.5MHz --- Shouldn't this be 200mhz???
FSBRAM CPU/26
CAS# Latency 2.5clocks
RAS# 5
tRAS 13
tRC 22
Command Rate 2T
DRAM Idle Timer 16 clocks

Any ideas?

 

[SlowSpyder]

Yup, it should be 200MHz. Check your BIOS settings. It should be auto, if that doesn't work try to set it at 200MHz, if your HTT is at 200MHz.

If you are running 2x1GB you should be able to set your Command Rate at 1T as well, it's worth a few percent in benches. When/if you go to 4x1GB you'll probably have to run that at 2T again.

Not sure what to expect on the overclock, each chips is different. But, my 165 ran at 2.7GHz pretty well, I'd think you'd get at least that on water.

 

[Grunt76]

Oh man, BIOS was not at auto, but manual. So manual 200mhz means 200mhz DDR and auto also displays 200mhz, but in that case it means 400mhz DDR.

UGH. I have no idea how long I've been running it like this.

Damn, now I want to load a game, see what kind of difference this makes.

Thanks

 

[Rhoxed]

^^ i second slowspyder

I have a 939 3800+ @ 2.7 on air

make sure you run Command Rate in 1T mode if its stable (no reason it shouldnt be if you dont OC)
you have ddr 400 which should be 200Mhz, for some reason you are running at ddr 200
you can also try to tighten timings a bit, i was running some Corsair XMS 2x1GB @ 2.5-3-3-6-1T

 

[cubeless]

2t mkaes a much bigger difference on amd than intel chips... u really want to get to 1t if possible... i run my memory slower in some cases to get 1t... amd wants low latencies more than high speeds...

 

[Grunt76]

Thanks for your help guys. I just doubled my framerates in all my games... D0h... XD

I'll try that 1T thingie

 

[SlowSpyder]

Originally posted by: Grunt76
Oh man, BIOS was not at auto, but manual. So manual 200mhz means 200mhz DDR and auto also displays 200mhz, but in that case it means 400mhz DDR.

UGH. I have no idea how long I've been running it like this.

Damn, now I want to load a game, see what kind of difference this makes.

Thanks

Yup, set it at 200MHz, that is 400MHz DDR speed. The northbridge shouldn't have much (anything??) to do with memory speed, the memory controller is on the chip with the A64/Opterons. Anyway, make that switch to 200MHz and see what you get in Sandra again. I would imagine you'll score much better. I have no idea what actual affect running the slower memory would have had in real world apps/games though.

 

[BTRY B 529th FA BN]

you'll really see the speed picking up @ 2.9Ghz +

my old system has ddr 566 with an fx60 and the extra memory bandwidth was noticeable ... think i ran an 11 multi at 2.86 but i think my pos mobo held me back A8R32 deluxe