I have a single quad-core cpu, but seti thinks I have 8. Why is that? Why not just 4? One for each core?

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I have a single quad-core cpu, but seti thinks I have 8. Why is that? Why not just 4? One for each core?

I suspect it would be because you have HT enabled in your bios settings, making the CPU act like an 8 core processor.

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"Freedom is just Chaos, with better lighting." Alan Dean Foster

Which would be better? HT or NO HT?

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Which would be better? HT or NO HT?

If you are running at or close to stock CPU speed, most folks tend to see a little better Seti performance with HT on.
If you are trying to OC the CPU speed, might be better with it off.
HT also tends to work better if you have fast RAM. It may not benefit as much with middle of the road memory speeds.

In either case, it will not hurt you to leave it on, most of the time the differences are fairly small.

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"Freedom is just Chaos, with better lighting." Alan Dean Foster

That would be correct. The 8 cores you see are actually 4 cores, each split into 2 logical cores, from the results of HTT or Hyperthreading. Here is a link on Hyperthreading that will help better clarify what it is you are seeing.

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http://www.goodsearch.com/nonprofit/university-of-california-setihome.aspx

As I mentioned elsewhere, there is a particularly poignant consideration concerning HT in this unfortunate environment of calculated task quotas....

As I mentioned elsewhere, there is a particularly poignant consideration concerning HT in this unfortunate environment of calculated task quotas....

True enough, you will get twice the quota for the CPU with HT on, as Boinc considers both the real and virtual 'cores'.
However, most folks are more concerned with keeping their faster GPUs fed, not so much the CPUs. (Unless you are also using the rescheduler to offload tasks from CPU to GPU, but that's another story, I guess).

With more than one, or a very fast GPU, I would still recommend idling 1 core on a quad, or 2 cores on a quad-HT, to better handle loading tasks into the GPUs.

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"Freedom is just Chaos, with better lighting." Alan Dean Foster

What I did was throttled it back to use just 2 cores. This keeps everything cooler, plus it allows a little more overhead for the GPU.

Thanks for your help!!!!!

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HT conciderations regarding optimal GPU support in a resource contentious environment is heavily host configuration dependent.On my configurations the multiple GPUs are running at 99% with all CPU cores (logical and physical) enabled. This has only been true under 290.36, and 41g, and on my configurations, and those I have tested, which are uniformly uber speced.

I thought Core 2 Quads weren't compatible with HT technology?

Core 2 Quads don't have HT, But Randy Moore's Quad is an Intel(R) Core(TM) i7 CPU 965 @ 3.20GHz

Claggy

...
True enough, you will get twice the quota for the CPU with HT on, as Boinc considers both the real and virtual 'cores'.
However, most folks are more concerned with keeping their faster GPUs fed, not so much the CPUs...

Indeed, you can get both effects just setting BOINC to use all the cores and then changing the avg_ncpus and max_ncpus tags in the app_info files for all the GPU tasks... For example, if you have 2 GPUs, running 2 tasks each, setting the CPU usage of the GPU's tasks to 0.25 will reserve one core, as the number of cores reserved will be allways the integral part value of the sum you can even set it to reserve a different number of cores depending on the combination of running tasks.

This way BOINC will report all the CPU cores (and your limits will be higher) but the GPU apps will be preventing some of them to be used (works with BOINC 6.10 and 6.12, not sure about other versions).
There is an added beneffit, if the GPU cache gets dry, BOINC will be able to run more CPU tasks... (which is also a drawback if you want to leave some free cores for other non Boinc apps or to avoid too much heat...)

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