Roberto Safora Romay queries:

"What those 83 Mhz mean'

The "83 Mhz" means 83 megahertz., it is a speed indicator.

Roberto also asks:

"Which are the elementary things to watch when it comes to mix extension
chips on video cards?"

I don't know about video cards, but with RAM, the memory SIMMS need to
be the same size and speed within a memory bank to work.  If you have
mixed and matched, you are probably running into the same problem.

--Sam Smilie

Yes Sam; but  I am asking if those 83 Mhz implies something. (bus speed, or
something like that)
The chips on board and the ones on the expasion seem to be the same
speed(35).
Thank you