mixing 4 x 4GB RAM with the original 2 X 1GB RAM??

[Kevin Camp]

if you move the original 2x1gb sticks from slots 1 & 2 of the top riser to slots 3 & 4 of top riser you should be ok. this will give you all the same size ram in slots 1 & 2 of both risers, getting the performance gain from the interleaving between them, but also giving you a bit more ram for other processes….

i guess there is still some potential performance loss due to the fact that you can’t specify that ae only use the 16gb in slots 1 & 2 of both memory risers, so it could use some of the original ram in slots 3 & 4, but i do think that it is likely that you would see little to no difference, and there should not be any stability issues from the extra ram.

now, i have read that if you fill all 8 slots you can eek out around a 10% performance boost… this is most likely due to the extra interleaving between both risers when all slots are full. so you may be able to get a little faster performance by adding 2x1gb sticks slots 3 & 4 of the lower riser to match that of the upper riser… and you may be able to find original 2x1gb sticks of mac pro ram cheap on ebay.

note that the performance boost tests i have seen have been using ram benchmark tools, not real world performance test, so take them for what they are worth….

Kevin Camp
Senior Designer
KCPQ, KMYQ & KRCW