Sign in with
Sign up | Sign in
Your question

Fastest Lower Price Computer Build to Add Gigabyte Sized Arrays

Last response: in CPUs
December 9, 2010 4:27:12 PM

Hi Y'all, :hello: 

I write scientific programs that use recursive addition of large arrays.

Literally take a 421x421x421 array, add it to another 421x421x421 array and save it to memory and repeat. Of course all with double floating point precision.

Obviously, the main memory bandwidth is my bottleneck. The number of cores doesn’t directly help because each core would be pulling more data through the front side bus.

I would love a $3000 double precision CUDA card, but that isn’t going to happen.

Now, an I7 with the fastest DDR3 memory would work, but I want to build a small army of these machines and can’t afford the high unit cost, plus most of the cores wouldn’t be used.

I been eyeing low cost 3.3 GHZ dual core AMD processors with 2.6 hyperlink front side bus and 16 gigabytes of 1066 DD3 memory but have ran into some questions.

First thing, is it my memory bandwidth or my front side bus that is my bottleneck? I can easily write my code for more cores if the main memory subsystems can take the stress.

Clearly, L2 and L3 caches mean very little when adding large arrays, so how cheap a processor can I go with? Will all modern processors add and save main memory at bus speed?

In other words, if I have the AMD 2.6 hyperlink front side, what is the minimum processor speed that can add memory arrays at DDR3 speeds?

What’s the lowest cost memory I can go with? For example my DD2 800 memory has a CAS access time of 5 and the DD3 1066 memory I have been looking has a CAS of 9.

Because of the different CAS’s, I’m not sure which memory has more bandwidth.

In other words, I don’t care about the fastest access times; I care about memory bandwidth per dollar. I don't care about processor speeds, as long as it can add and save memory at bus speeds.

So, with these design requirements what build would you use to build a small army of these machines?

AMD or Intel is ok, I assumed AMD is the better deal.


a b à CPUs
December 11, 2010 3:38:01 AM

Personally, i would wait until the middle of Q1 2011,( that is about February) Both AMD and Intel will have new tech out. You may see a 5-15% improvement on the new may be more expensive, but it will 'future proof' your system for years.
a b à CPUs
December 11, 2010 3:38:22 AM

Oh, BTW:

Welcome to the Guide.
December 18, 2010 12:46:52 PM

I ended up getting a 2gb GTX 460 card. Learning Cuda c now.

Turned out that I7 was the best bet, not because of the processing power but because of the three channel memory support.

The AMD solutions are a good buy, I could buy two of those for every I7 machine and the dual channel memory 1600mhz DD3 support would still be in the ballpark.

Overall, the Cuda card with GDDR5 memory was the best bet, mostly because of the memory.