Very strange phenomea, I see much higher Mhash/s than I am supposed to see

[iamthelittleone]

Well, I am mining using the GUIminer, using deepbit, and the GUIminer interface shows that I have got about 64 MHash/s, but strangely, the deepbit interface, the website, says that my avg speed is 82 MHash/s.

How is this possible? Which is right?

[epicCreations.org]

I see the same phenomena. I have 2 Mh/s but it sometimes reports around 15

[iamthelittleone]

So, which is the right one?
And why are there differences?

Anyone?

[Houseonfire]

You are correct. I noticed the same thing before.
I thought it was because i did an Overvolt and massive overclock of my FSB and CPU but I guess not.