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Author Topic: Large difference in mining speed between two machines with same processor  (Read 871 times)
meisterchango
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June 13, 2011, 07:21:02 PM
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I have two machines, both HP laptops theoretically based around the same processor, namely an Intel i7 Q 720. They're not absolutely identical models, but they're similar-ish in various other respects: both 4 GB machines running Windows 7 64-bit. So I wouldn't expect them to achieve absolutely identical mining rates.

But in practice, one of the machines achieves a rate of ~5.5 - 6 Mhash/s, whereas the other hovers at around 50 Mhash/s, i.e. almost TEN TIMES greater. I've played around a bit with number of threads on both machines, and these seem to be pretty much the maximum achievable, give or take a few per cent.

Now in all honesty, I'm not interested so much in BitCoin mining as a means to fame and fortune. But it did get my wondering: what can be so different about these machines, based on the same processor, that one should perform TEN TIMES better than the other? Is there something about the mining task that can give some particular configuration (e.g. memory type?) such an advantage? I'm kind of interested because the one performing 10 times slower is my "main" machine, so if there's some configuration change I can make that will make OTHER tasks run several times more efficiently, I'd kind of like to know. Equally, if there's some problem with the CPU on the "fast" machine that's meaning it's not controlling some aspect of itself properly that might make it fry (but see below), I'd also kind of like to know.

From temperature monitors and TurboBoost monitor, both machines behave roughly similarly, with CPU speed tending to hover around the nominal speed or just slightly higher (e.g. the 1.60 GHz is typically boosted to around 1.73 GHz, say), and with both machines running at a temperature around 10 degrees below the max.

So... can anyone think what kind of thing might be involved here to make such a difference?
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Gabi
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June 13, 2011, 07:26:46 PM
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Are you sure the other machine isn't mining with a GPU?  Grin

I doubt a cpu can reach 50Mhash/s...
meisterchango
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June 13, 2011, 07:39:02 PM
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Are you sure the other machine isn't mining with a GPU?  Grin

I doubt a cpu can reach 50Mhash/s...

OK, I suppose now you say it I'm not *sure*. But this is what I can tell you:

- I'm using GUIMiner with "Ufasoft CPU miner" as the miner
- I'm using that because when I try to use one of the supposed GPU miners I'm told "no OpenCL devices detected"
- detected or not, the machine actually has an "ATI Mobility Radeon HD 5650"
- the miner is definitely using CPU-- this is obvious from the task manager, and from general behaviour (e.g. specifying only 1 or 2 threads makes the CPU turbo faster, which is what the i7 is supposed to do if just a few cores are given extra load). Whether it's using CPU *and also* the GPU, I suppose I'm not sure... Does anyone know about "Ufasoft CPU miner"...?
meisterchango
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June 13, 2011, 07:55:10 PM
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Thanks guys! Didn't realise the Ufasoft "CPU" miner also used GPU. That reassures me there's nothing wrong with the configuration of my machines!
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June 13, 2011, 08:11:07 PM
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Be super careful laptop mining. They can be prone to overheating!!! (learned the hard way)

Airport security wouldn't let me through with my Origami Dagger, but I got by with the paper to make Origami Hand Grenades!
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