user12014: I have one computer with windows 8.1 13.11 driver and a 280x which gets 720KHS and another computer with the same setup which gets 620KHS.
They have a different cpu ram and psu (both have quality ones).
How can this be?

user5651: 
I have one computer with windows 8.1 13.11 driver and a 280x which
  gets 720KHS and another computer with the same setup which gets
  620KHS.
They have a different cpu ram and psu (both have quality ones).
How can this be?

It's because they have a different ram. With scrypt mining RAM is of up most importance. The faster/higher quality the ram, the faster you can mine.
Scrypt was made to require ram so it would slow down the over all hashing power and to resist asics.

12014: <p>I have one computer with windows 8.1 13.11 driver and a 280x which gets 720KHS and another computer with the same setup which gets 620KHS.</p>

<p>They have a different cpu ram and psu (both have quality ones).</p>

<p>How can this be?</p>
 5651: <blockquote>
  <p>I have one computer with windows 8.1 13.11 driver and a 280x which
  gets 720KHS and another computer with the same setup which gets
  620KHS.</p>
  
  <p>They have a different cpu ram and psu (both have quality ones).</p>
  
  <p>How can this be?</p>
</blockquote>

<p>It's because they have a different ram. With scrypt mining RAM is of up most importance. The faster/higher quality the ram, the faster you can mine.</p>

<p>Scrypt was made to require ram so it would slow down the over all hashing power and to resist asics.</p>
