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Low memory bandwidth problem - Page 4

post #31 of 35
Thread Starter 
Thank you very much for your help and a nice welcome to the board.

I'm going to buy those Kingstons then. Geils are my plan B just in case. I'll post my results in the upcoming days.
post #32 of 35
Thread Starter 
Hello. I replaced my ram with these Kingstons but am struggling to find the correct settings. Out of the box at 800mhz at cl4 they give me ~7gbit/s memory bandwidth which is a bit better than my previous ram after OC.
However I can't overclock my CPU as well as I could with my previous memories. Because with memory clock multiplier at x4 when I OC my CPU even by a bit my RAM can't handle even a dozen of extra mhz. I have to lower the memory clock multiplier to x3,33 which makes my system detect them as 667. However in that case I can't make my RAM reach their 800mhz clock speed because of x3,33 memory clock multiplier. It's at about 750-770mhz with the optimal CPU clock speed. I mean - it's still quite fast with these settings but the fact that my bios detects them as 667mhz and that in reality they still work below their stock speeds makes me wonder if there's anything I could do.

edit: At the same CPU clock I tried to:
1.set my ram multiplier to x4 and timings to cl5
2.ram multiplier to x3,33 at cl4.
The first one gave me more memory-copy speed and slightly better hyperpi (0,2s for a 1M digits count) score but higher access times.

Actually it makes me wonder if there's another, better option.

edit2: Okay, so it turns out that every benchmark gives me better results with higher clock speeds at cl5. Does it mean that getting 1066mhz cl5 ram would be a better idea?
Edited by szymon247 - 11/23/10 at 2:42pm
post #33 of 35
750-770Mhz is not too bad. You could try lowering timings to compensate but considering how big the jump is in DDR2 I doubt you could go very far. Memory-copy speed is basically a combination of read-write. 1066 CL5 could be a better idea; it might scale better than 800 CL4 depending on your CPU-NB clock.
post #34 of 35
Thread Starter 
Well, they easily run at ~780mhz cl4 or 936mhz cl5 at cpu fsb that I decided to use. I could overclock my cpu fsb further and these memories could handle that too but I decided to settle with a bit lower setting for extra safety (regarding CPU stability). At cl5 I know that they booted at 1000mhz but I didn't test them for long because it's usually more than max overclockability of my CPU.
Would it be worth replacing these for 1066mhz cl5 RAM sticks for 30$ more or is it not really worth the performance gain?
After all I think the difference between my previous 667mhz cl5 and my current 800mhz cl4 is probably bigger than between 800mhz and 1066mhz and I can't really feel that much of a difference. Also, I'm not sure if they would scale well unless they would work at 936mhz cl4 or ~1200mhz cl5 but I'm also not sure if my motherboard could handle that.

Now a pretty strange part: I downloaded 3dmark06 since it's better at showing real gaming performance and I get similar results no matter if everything is at stock settings or if everything is overclocked with memories either on cl4 or cl5. Overall 3dmark06 score is almost equal with my CPU and RAM at stock settings, despite giving a lower CPU score.
Basically after overclocking I'm getting a bit higher CPU score than I get at stock settings which is at around 4000, after overclocking my cpu fsb with RAM at cl4 I'm getting a bit above 4400 and with higher clocked RAM at cl5 it's almost 4500. Still, the difference is very small and sometimes the difference between 2 random 3dmark06 runs on the same setting is bigger than the difference I get after changing my ram settings.

I'm not sure which settings to keep.

edit: Okay, I summed up all of my test results and looked for the highest median result. Left it at cpu fsb @224 so my CPU clock is at 3250mhz and ram at a corresponding speed with x4 multiplier and cl5. Seems to give me best results, slightly better than when my ram is at cl4 and lower clock speeds.
Edited by szymon247 - 11/24/10 at 11:21am
post #35 of 35
For $30 more I wouldn't consider it that work it. If you're happy with the difference already, then stay where you are considering it probably works just fine I don't think 3DMark06 is very memory-dependent (unless with a GPU memory overclock).
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