Intel i7-3770K vs. i7-3820 for molecular dynamics.

officerping

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Sep 20, 2012
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Hi there,

I'm trying to decide between two workstation builds:

https://dl.dropbox.com/u/5381783/build.pdf

https://dl.dropbox.com/u/5381783/build2.pdf

The components are all the same, except for the motherboard and CPU. One is the i7-3770K, an Ivy Bridge processor; the other is the i7-3820, a Sandy Bridge-E processor.

A few components are missing (power supply, storage HD, video card) because I plan on salvaging them from existing boxes. I have two GTX 480's and a GTX 470 that I plan to install, but in the future we might upgrade them to GTX 680 or whatever comes out in the future.

My application is scientific computing. I need this box to do two things mainly:

1) Rapid execution of single-threaded processes on the CPU 2) High bandwidth and low latency for communication between the CPU and GPU

From what I've heard, the i7-3770K (Ivy Bridge) has the following advantages:

1) More rapid single thread execution by 10-20%.

2) Supports PCI-e 3.0, whereas Sandy Bridge doesn't (?) I've gotten conflicting evidence over this: (http://www.anandtech.com/show/5264/sandy-bridge-e-x79-pcie-30-it-works). Only the newest graphics cards support PCI-e 3.0, so this pertains to upgradeability and not the present GPUs.

3) Supports USB 3.0 whereas Sandy Bridge-E does not? This isn't a primary requirement, but since this is a workstation, rapid data transfer to external drives is a big plus.

4) Smaller transistors are "cooler" :)

The i7-3280 (Sandy Bridge-E) has the following advantages:

1) More memory bandwidth (quad channel, vs. dual channel for Ivy Bridge)

2) More PCI-E lanes for greater GPU/CPU communication bandwidth (40 lanes, vs. 16 for Ivy Bridge)

I'm leaning towards the Sandy Bridge-E processor because of the greater bandwidth. Some people say I don't need 40 PCI-E lanes with two GTX 480 cards - however, scientific computing applications can require very high data throughput (I don't know how to measure exactly how high) and it would be great to have a machine where bandwidth is not an issue. I think this is potentially more important than the performance boost on single thread execution that I'd get from the Ivy Bridge.

Overclocking is a minor concern. I've never overclocked any CPU (even though I've assembled 20+ boxes over the years), and when it comes to work-related hardware I am relatively risk-averse. That said, if one of the CPU can be more easily overclocked by a minor amount, it might affect my decision.

Thanks for reading!
 

officerping

Honorable
Sep 20, 2012
3
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10,510
An additional note - I'm running molecular dynamics simulations such as GROMACS, TINKER, OpenMM and AMBER. Some of these are single thread processes and others aren't; some of them run on the GPU.
 

officerping

Honorable
Sep 20, 2012
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10,510


It's tough to determine bandwidth requirements because the data throughput of these jobs is not well characterized or easily measurable.

I would like to have a box where bandwidth is maximized, if only for the purpose of testing whether throughput is a bottleneck or not.