Optimising AMD cards for maximum efficiency

Message boards : Questions and problems : Optimising AMD cards for maximum efficiency
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Setonix

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Joined: 6 Jun 17
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Message 79044 - Posted: 15 Jun 2017, 17:07:19 UTC

I currently have 2 x 7790s happily chugging away on collatz on a dualcore E7200; and

2 x 5750s working on einstien, also with an E7200.

I would like to optimise these machines. I might even try to cram all four cards into the one machine if the PSU will take it (If I get another).

I have had a quick scratch around re optimising, but are there any resources to get me started?

Also, I notice that the GPUs will use 0.8xx of a CPU core, and thus, between them, there is about a core wasted or being wasted just CPU crunching.

Is it possible I could put a third card into the same case and run 3 GPUs on a dualcore CPU? How about FOUR GPUs??

Thanks again.

Mark
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ProfileAgentb
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Message 79052 - Posted: 15 Jun 2017, 22:05:35 UTC - in response to Message 79044.  
Last modified: 15 Jun 2017, 22:07:31 UTC

You will get many different opinions and all will be right!

My 0.02 gbp

Firstly different applications use GPUs in very very different ways and different configurations and operating systems will be optimal.

The rule of thumb leaving a CPU free is just that.

I have seen as many as 8 GPUs however even with two GPUs, a case (and then room) cooling becomes THE issue.

As the number of cards increase the PCI / CPU / RAM bottlenecks start to have an impact.

Quad channel 4x2GB memory will be a lot faster than 1x8GB for certain apps.

All i would say is develop your method this is roughly what i do

Stability is the main thing for me restarts and crashes are bad, for all reasons.

Look at the applications you want to run and which suit your hardware / memory/ VRAM etc read forums etc

THEN

- choose OS you are confident in
- be absolutely certain the cooling and power are up to the task - i can't stress this enough. Overspend on PSU and case cooling. Efficient PSUs pay for themselves and reduce case and room temperatures.
- start from a simple base line - run each application / GPU solo to get a baseline for each application
- record stable run (and validation success) times over steady state.
- Monitor temps, CPU, memory and power usage - build a spreadsheet and this will help over the life - you can go back to see what the temps were when you started and see if it is running hotter or slower.
- if you are getting invalids or errors stop and find out why - you can't tune a faulty engine.
- increase task loads and keep recording run times and temps etc.
- the fewer GPU apps you run the more stable. For example you may find running project X one month then project Y the next is more stable than running X and Y at the same time.
- overclock by small amounts over long periods (if you must).
- stability trumps speed. %(errors+invalids) should be <0.5% imho. If you monitor one thing monitor this stat.
- ignore CPU crunching until you have the GPU side optimised - and what optimal exactly means depends on what you want. Power / temp / times etc
- repeat for CPU tasks disabling GPU.
- return to the GPU and start adding the CPU tasks and see how they affect GPU times.

- call it done, and leave it you can spend too much time...

good luck
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Setonix

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Message 79054 - Posted: 15 Jun 2017, 23:39:51 UTC - in response to Message 79052.  

Agentb, ta for your response.

I am running a Intel dp45sg (Extreme) motherboard, which is an old 775. I thought it was dodgy, but it has not missed a beat with its new task.
http://ark.intel.com/products/34683/Intel-Desktop-Board-DP45SG

I am running 4 x 2G memory as mentioned, and this board has 4 PCIe ports and wit a little ingenuity, I am sure there is enough capacity for it to support at least 3 GPUs.

The case is quite an open gamer's case with a huge fan in the roof of it, and I can turn it into a veritable wind tunnel if need be.

I am running a clean install of Win7 pro and i have not had any system instability whosoever.

As mentioned, I am running a dual core E7200 which I chose for its efficiency, but if you believe it worthwhile, or needed for running 3 or 4 GPUs, I have several (more thirsty) quad cores like the Q9650 that are currently doing nothing. Is it worth it or needed to have those extra cores?
http://ark.intel.com/products/35428/Intel-Core2-Quad-Processor-Q9650-12M-Cache-3_00-GHz-1333-MHz-FSB
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ProfileAgentb
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Message 79072 - Posted: 16 Jun 2017, 19:29:31 UTC - in response to Message 79054.  

, I have several (more thirsty) quad cores like the Q9650 that are currently doing nothing. Is it worth it or needed to have those extra cores?
http://ark.intel.com/products/35428/Intel-Core2-Quad-Processor-Q9650-12M-Cache-3_00-GHz-1333-MHz-FSB

To repeat - you need to look at the applications you want to run - some apps use virtually no CPU, and offload it all to the GPU. I can't help you with that, you have to make a choice.

You are worried about maybe 20W on a CPU with 2x180W GPUS smoking away in the case (or more) ? Really?

I think for the same load the quad core would use a lot less power and be more efficient per watt. The quad core has more L2 cache and higher bus speed.

Some apps benefit a lot from a fast CPU to drive the GPU - pushing data in and out of RAM, you can't make a steam engine go fast with a plastic teaspoon to shovel the coal.
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Setonix

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Message 79079 - Posted: 18 Jun 2017, 9:18:57 UTC - in response to Message 79072.  

Point taken onboard - fair call. 12M cache and all.

This is an ongoing project of learning and there is HEAPS I don't know. It is all obvious in hindsight, but it is impossible to take it all in and be across the lot at first glance.

Thanks again.

Mark
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Message boards : Questions and problems : Optimising AMD cards for maximum efficiency

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