New Mac Pro Ram confusion, can you help?

[cydspal]

Sorry, but I am still confused and want to make sure I buy the correct Ram, can you help? I just bought a Mac Pro two 2.8 quad core, is this the way to go? "Put each pair in the AB slots top and bottom ram cards plus the pair of 1GB sticks that came with it in CD of the top ram card"

So that's:
4.0GB Mac Pro Memory Matched Pair (2GB x 2) PC6400 DDR2 ECC 800MHz 240Pin FB-DIMM Modules .....right?

I cant afford much more than the two 2gb for now, but.....then I read this on Bare feats:

Some of you just want to buy two 2GB FB-DIMMs to add to the two factory 1GB FB-DIMMs for a total of 6GB. That configuration will slow you down. Don't do it. Again, the BEST performance setup is eight matched FB-DIMMs. The second best is four matched FB-DIMMs.

What to do?

 

[netdog]

You could also buy 2x1GB sticks instead. That won't slow you down and you will have 4GB of RAM in total. Don't know if that amount would meet your needs.

Later, you could add another 4x1GB for 8GB total or 4x2GB for 12GB total. I believe those configs would not slow you down either.

Finally, you could do what I did and sell your 2x1GB sticks that came with the machine and buy 4x2GB sticks from OWC. I think they are now $429+shipping. If you are in the UK, add another 17.5% for VAT when the RAM clears customs with FedEx.

 

[Luis Ortega]

Finally, you could do what I did and sell your 2x1GB sticks that came with the machine and buy 4x2GB sticks from OWC. I think they are now $429+shipping. If you are in the UK, add another 17.5% for VAT when the RAM clears customs with FedEx.

I just ordered 4 x 2GB from OWC myself for when my Mac Pro arrives.
Did you already receive yours? How long does it take to arrive?
At what point do you pay for the VAT? OWC did not add that to my cost.

As for the 2 x 1GB that comes in the Mac Pro, are you saying that it's best not to put them in?
If you did put them in, would they go one on each riser or both on riser A?

If I hold on to them for a bit until UK Crucial starts to sell the correct ram then buy another 2 x 1GB will the fact that the two sets are likely from different sources mean that compatibility or stability problems will arise?

I noticed on the Crucial site that their ram may come with a different, lighter heat sink compared to the bigger-finned ones that OWC show and Apple use. Would this be a problem and should buyers demand that the heat sinks be the more robust ones that OWC and Apple use?

Thanks for your advice.

 

[rds]

I just ordered 4 x 2GB from OWC myself for when my Mac Pro arrives.
Did you already receive yours? How long does it take to arrive?
At what point do you pay for the VAT? OWC did not add that to my cost.

The courier will ask you for the 17.5% VAT.

As for the 2 x 1GB that comes in the Mac Pro, are you saying that it's best not to put them in?
If you did put them in, would they go one on each riser or both on riser A?

Put the OWC memory in risers 1 and 2 of each 'memory card' and the Apple ram in 3 and 4 on the top. If you want quad channel, you would have to leave out the Apple memory. Personally, there is not much real world benefit so I would have the full 10GB instead of 8GB.

If I hold on to them for a bit until UK Crucial starts to sell the correct ram then buy another 2 x 1GB will the fact that the two sets are likely from different sources mean that compatibility or stability problems will arise?

The reason people are talking about SETS of 4 and 8 is for quad channel memory, only if you buy a MATCHED SET of 4 will you benefit from quad channel, much in the same way as MATCHED PAIRS will give you dual channel memory performance.

 

[Umbongo]

The reason people are talking about SETS of 4 and 8 is for quad channel memory, only if you buy a MATCHED SET of 4 will you benefit from quad channel, much in the same way as MATCHED PAIRS will give you dual channel memory performance.

Do you know anywhere where this is officially stated, either Apple, Intel or another board manufacturer? Not that I am denying it, but I couldn't find anything saying that memory capacities need to be the same, just that 4, 8 or 16 DIMMs were needed.

 

[pfleischman]

Do you know anywhere where this is officially stated, either Apple, Intel or another board manufacturer? Not that I am denying it, but I couldn't find anything saying that memory capacities need to be the same, just that 4, 8 or 16 DIMMs were needed.

I agree with you, no where does it say that they have the be the same size. I does say they have to be there though. I have other posts that go into in more detail.

 

[cydspal]

Ok, since the Mac Pro comes with an entry level 2 x 1gb, wouldn't it be best to buy 6 x 1gb cards so that you would have 4 x 1 gb on the bottom and 4 x 1 gb on the top? I guess the downside is the slots are now full at 8gb and the debate on if its better to toss the 2 x 1gb cards and go for just 4 x 2gb cards to keep it all equal and go for the 4 card sweet spot as per barefeats.