Memory Timings and Dram Frequency

TheThreeDegrees

I was wandering how come the ram performance seems to drop whenever I push the FSB?

Latency
Core 2 Quad Q6600 3300 MHz X38 Dual DDR2-917 4-4-4-12 CR2 57.6 ns

Copy Speed
Core 2 Quad Q6600 3300 MHz X38 Dual DDR2-917 4-4-4-12 CR2 7419 MB/s

Write Speed
Core 2 Quad Q6600 3300 MHz X38 Dual DDR2-917 4-4-4-12 CR2 6657 MB/s

Read Speed
Core 2 Quad Q6600 3300 MHz X38 Dual DDR2-917 4-4-4-12 CR2 8376 MB/s



Latency
Core 2 Quad Q6600 3315 MHz X38 Dual DDR2-921 4-4-4-12 CR2 58.0 ns

Copy Speed
Core 2 Quad Q6600 3315 MHz X38 Dual DDR2-921 4-4-4-12 CR2 7383 MB/s

Write Speed
Core 2 Quad Q6600 3315 MHz X38 Dual DDR2-921 4-4-4-12 CR2 6656 MB/s

Read Speed
Core 2 Quad Q6600 3315 MHz X38 Dual DDR2-921 4-4-4-12 CR2 8369 MB/s

TheThreeDegrees

What I do notice that if the ram is set at the same frequency as the FSB (ratio1:1)some operations are far quicker and yet some are worse.

Latency
Core 2 Quad Q6600 3600 MHz X38 Dual DDR2-800 4-4-4-12 CR2 59.9 ns

Copy Speed
Core 2 Quad Q6600 3600 MHz X38 Dual DDR2-800 4-4-4-12 CR2 7748 MB/s

Write Speed
Core 2 Quad Q6600 3600 MHz X38 Dual DDR2-800 4-4-4-12 CR2 7265 MB/s

Read Speed
Core 2 Quad Q6600 3600 MHz X38 Dual DDR2-800 4-4-4-12 CR2 7971 MB/s



And with looser timings the Frequency increases and so does the Memory performance.


Latency
Core 2 Quad Q6600 3600 MHz X38 Dual DDR2-960 5-5-5-15 CR2 59.1 ns

Copy Speed
Core 2 Quad Q6600 3600 MHz X38 Dual DDR2-960 5-5-5-15 CR2 7900 MB/s

Write Speed
Core 2 Quad Q6600 3600 MHz X38 Dual DDR2-960 5-5-5-15 CR2 7264 MB/s

Read Speed
Core 2 Quad Q6600 3600 MHz X38 Dual DDR2-960 5-5-5-15 CR2 8467 MB/s

and tighter timings at 1:20

Latency
Core 2 Quad Q6600 3600 MHz X38 Dual DDR2-960 4-4-4-12 CR2 56.5 ns

Speed
Core 2 Quad Q6600 3600 MHz X38 Dual DDR2-960 4-4-4-12 CR2 8010 MB/s

Write Speed
Core 2 Quad Q6600 3600 MHz X38 Dual DDR2-960 4-4-4-12 CR2 7264 MB/s

Read Speed
Core 2 Quad Q6600 3600 MHz X38 Dual DDR2-960 4-4-4-12 CR2 8734 MB/s

jasperok

i think its something to do with the way intel chisets work
They respond well to high MHZ as they dont have an on chip memory contorller like AMD
Not sure why lower latency is hurting your timings for the same mhz on each run but maybe it has something to do with the memroy controller to.
how many times did you run the test?
try it 3 or more times at each setting and get averages.

nibble

Could be strap loosening, even when the actual strap doesn't change other internal chipset latencies can too.. Or could just be margin of error? Did you do multiple runs, because I always get slightly different results at the same clocks/timings.

TheThreeDegrees

Ok ran them again and this time got higher results with the higher FSB.ah well.