Why does my hash rate vary?

[pletharoe]

I'm using a KnC Jupiter, although this question should apply to any machine which is only used for mining.

Chip clock speeds are constant.  If there is unlimited access to work (I believe this is the case with most pools), why does the miner's hash rate vary with time?

[Flashman]

Because it's all an average.

Say it's all potatoes, you can peel 4 potatoes a minute on average. But, sometimes you get small smooth ones that take only 7 or 8 seconds, sometimes you get big knobbly ones with lots of eyes that take 30 seconds plus. So you reach into the bag and get another tater and start peeling, sometimes you get lucky and get 10 small smooth ones in a row and your "rate" looks great, but then you have a run of big knobbly ones and you slow down again.

[pletharoe]

Thanks for the spud analogy!  I hadn't realised that some hashes are harder to calculate than others.

[MTBmanTT]

Because it's all an average.

Say it's all potatoes, you can peel 4 potatoes a minute on average. But, sometimes you get small smooth ones that take only 7 or 8 seconds, sometimes you get big knobbly ones with lots of eyes that take 30 seconds plus. So you reach into the bag and get another tater and start peeling, sometimes you get lucky and get 10 small smooth ones in a row and your "rate" looks great, but then you have a run of big knobbly ones and you slow down again.

Thats a pretty good analogy, I like that.

[madcratebuilder]

Damn, I want some French fries, good analogy.

[eleuthria]

Thanks for the spud analogy!  I hadn't realised that some hashes are harder to calculate than others.

Technically all hashes are the same difficulty to calculate/time to generate.  The difference is, each one is a completely separate 256 bit output, and a 'share' is only a certain subset of them.  The traditional difficulty 1 share is approximately a 1 in 4.2 billion chance (or 4.2 Gigahashes).  So if you do 4.2 GH/s, you will on average get one per second.  Then it falls into the analogy above .

[overunity]

On my Usb sticks at Bitminter I noticed that a stale proof of work sends my hashrate to near zero .possibly cause of the tata effect hehe.

[leannemckim46]

Some time u get lots of french fries and sometimes less