how much memory will my mid 2007 imac hold

if it has 2 memory slots I think Apple say 4, and I had 6 (a 2 and a 4) in mine.

That is really what I suggested. 2 x 4Gb did work but tended to slow rather than speed up the machine. Apple's recommendation of 4Gb is, as usual, conservative.

I have been running 6Gb (1 x 2 and 1 x 4GB) with 10.6.8 Snow leopard for about 4 years. It works well. But putting in 8Gb (2x4) will not improve matters. My RAM came from OWC.

I tried 2*4 on my old machine and it failed..I think 6 may be the maximum.

Parvizu wrote:

How much memory will my mid 2007 Imac hold?

This link should help you identify the maximum memory for your computer.