Effect of ram speed on scrypt mining - a10-5800k

[buttons]

Just for those curious i ordered some visiontek cl11 2133 memory for my latest a10-5800k build.

Im going to put three 270x on the board, but was curious what the apu could pitch in.

1 stick of ddr3 at 1333 = 16kh
2 stick of ddr3 at 1333 = 44kh
2 stick of ddr3 at 2133 = 52kh

apu is at stock clocks, no fancy flags or thread concurrency. ubuntu 13.10 with amd driver shaders set to 384, intensity 13

 

[Track Drew]

Any chance you can manually set memory speed on your board? If so, for the sake of academics could you try testing:
1 stick @ 1600
1 stick @ 1866
1 stick @ 2133
2 stick @ 1600
2 stick @ 1866

And if by chance get the memory timings at each speed - including the ones above?

I'm curious about the impact of memory bandwidth and latency on OpenCL computing performance. Wondering what the point of diminishing returns is, how effective the memory controller is, is one stick @ 2133 better then 2 @ 1600, etc. Should be able to get a nice graph showing scaling over 1 vs 2 channels.

It's wild what a huge impact memory speed has, 16 kh/s is just above what my E-350 can do, but 52 is probably worth the power use.

 

[buttons]

It might be awhile, yet. i can say the A4-4000 gets around 29kh with dual channel 1333. Years ago with bitcoin mining, memory bandwidth didnt make any difference unless it was really really low. an a10-5800k would probably do 85kh, but with scrypt mining memory bandwidth plays a big role.

It may be awhile before i do any further testing. I put a 270x in that system and after fighting with ubuntu for about 4 hours just to get the 270x mining im not sure i want to touch it. I have a couple a10-5800k, and im building one for a cousin this weekend so i can try it then.

 

[pcjunkie]

Impressive. I bet the best bang for buck would be dual 1866 sticks if 2133 is a little pricey.

 

[Digital Viper-X-]

It might be awhile, yet. i can say the A4-4000 gets around 29kh with dual channel 1333. Years ago with bitcoin mining, memory bandwidth didnt make any difference unless it was really really low. an a10-5800k would probably do 85kh, but with scrypt mining memory bandwidth plays a big role.

It may be awhile before i do any further testing. I put a 270x in that system and after fighting with ubuntu for about 4 hours just to get the 270x mining im not sure i want to touch it. I have a couple a10-5800k, and im building one for a cousin this weekend so i can try it then.

BTC mining has very little dependence on memory bandwidth or latency, SCRYPT mining is VERY latency dependant, so if you can get lower latency memory, you will see a bigger boost.

 

[buttons]

thats interesting. I bought the 2133 because it was $19 a stick.

ill try 1866 with tighter CL. I just know with video cards you seem to get the best hash when the memory is set to 1500mhz and the GPU is 30% lower 1000/1500 , on my cards that wont run 1500 memory i set them to 860/1250 or something like that.