Will I notice a difference?

[CrayonMuncher]

if the mobo only has ddr3 slots then only ddr3 can be used not ddr2

ddr 3 is not backwards compatible with ddr2

 

[sirsaechao]

But does DDR3 800 RAM even exist? That's my ?. If I get DDR3 AM3 board I wouldn't keep 800 RAM...I would go up to the max but just wondering when they say DDR3 800-1800...were they referring to DDR2 800 instead but I see what you mean about backward compatibility issues.. I know...confusing...

 

[CrayonMuncher]

there is ddr3 800
ddr3 offers more benefits than just speed over ddr 2

 

[sirsaechao]

Indeed. I was going to upgrade piece by piece and was going to reuse the RAM but I will get the 945 then look for a new AM3 plus DDR3 RAM when the funds arrive.