friends I have a problem an

i had an intel i5 650 and 8 ram usable 7.92 gb
but to change the cpu i7 870 only 4 ram recognizes me
I set it both in the bios and it does not restart and it remains the same all in zero
(already updates the bios) how strange that the one that appears in the 1333mhz photo on the label says 1600
and as I said before if I had both a dual chanel mode and I just did was change the cpu

I thank you in advance