Sometimes, due to the slightly curved backing on the 8 series models, you *may* have to employ to different lengths of M8 bolts (screws). It can depend on which make/model mount you go with. YMMV.
Often the M8/45 mm generally work for Sammies (that's what I used for my 55" series 8), but only with the Sanus mount. My other 60", paired with a Echogear mount, required two 45mm bolts (top) and two 50mm bolts (bottom) to properly line up with the curved back/hole placement on mount arms. It also depends on whether or not a mount/installation requires you to use the plastic spacers (often for cable management, or to accommodate recessed holes for bolts behind HDTVs. Again, YMMV.
FWIW, don't buy the Samsung mount- it's overpriced. Look at a Sanus that can fully articulate/tilt/rotate for ~$129 online.
Hello- we just bought a Samsung Flat Screen 65 inch flat screen SUHD 8 series. We already have a nice tilt wall mount capable of holding 130 pounds, sufficient to hold the 50 pound Samsung. But there is some mystery as to what length and caliber of machine bolts are needed. I read it is an M8. But what length? I assume. I am not required to use Samsung's 'slim mount'. They sell thier own $200 tilt mount but it may not come with the screws either. Can anyone advise me on this please? Thank you!