Is Mac Pro RAM backwards compatible?

[syrinxfilms]

That is to say could I use 1066 MHz gen 4 ram in my Mac Pro 1,1 2.66 quad? I know it will clock down, but I want to buy a good chunk of Ram and future proof it a bit for an upgrade.

Thanks.

 

[Spanky Deluxe]

No it won't work. They use completely different types of RAM alas with the 2006 model using FB-DIMMs (fully buffered with the massive heatsinks).

2006/7 Mac Pro: 667 MHz DDR2 ECC fully buffered DIMM
2008 Mac Pro: 800 MHz DDR2 ECC fully buffered DIMM
2009 Mac Pro: 1066 MHz DDR3 ECC DIMM
2010 Mac Pro: 1066/1333MHz DDR3 ECC DIMM

All 2010 Mac Pro RAM will work in 2009 Mac Pros but no previous models.
No 2009 Mac Pro will work in previous models.
Some 2008 Mac Pro can (I believe at least) work in 2006/7 Mac Pros although the 2008 Xserve RAM I once tried in my 2006 Mac Pro didn't work.
2007 (Octo) Mac Pro RAM works in 2006 (Quad) Mac Pro machines and vice versa.

 

[syrinxfilms]

Thanks, that's good to know.