Faulty Ram Replacement

Question

Level 1

9 points

Faulty Ram Replacement

Hi Everyone,

I have a Mac Pro 3,1 with 4gb (4 x 1gb modules) ram running Snow Leopard.

Unfortunately I've recently started to see strange things happening in both OS X and Windows 7 via Boot Camp (separate hard drive).

This intern led me to look more closely at my hardware only to discover that 2 of the 1gb modules appear to be faulty.

So heres the questions...

Because I want to add another 8gb ram should I add it as 2 x 4gb or 4 x 2 gb? (gaming performance in Windows 7 is the key issue here).

Also with the 2 remaining 1gb modules, would they be best assigned to riser board A to give me a total of 10gb ram?

Finally, the best prices I've found come from these manufactures:

Crucial

Integral

Hynix

Elpida

Any recommendations as to which I should go with and configuration advice would be really appreciated.

Many thanks in advance

Mac Pro 2 x 2.8 • 4GB Ram, Mac OS X (10.5.4), Nvidia 8800GT • BenQ FP241W

Posted on Jun 12, 2012 3:39 PM

Reply

Answer 1

X423424X

Level 6

14,265 points

Jun 12, 2012 3:54 PM in response to David Mahony

I don't think it matters whether it is 4 x 2GB or 2 x 4GB.

As to where to put the dimms, that's model specific. So for a mac pro 3,1 (early 2008) this would be the layout:

Reply

Answer 2

David Mahony Author

Level 1

9 points

Jun 12, 2012 4:18 PM in response to X423424X

Thank you for the advice but I'm sure I read somewhere that to utilise the 256 bit addressing then the ram needs to be an equal number of matched pairs in the riser boards (4 x 2gb)????

Reply

Answer 3

Ricks-

Level 6

11,515 points

Jun 12, 2012 4:25 PM in response to David Mahony

You are correct. As long as you install in pairs you will have no problem.

I would choose the 4 GB modules. Cost today is pretty close for a pair of 2GB versus a single 4 GB module. Leaves you open slots in case more RAM would help.

Crucial (actually Crucial is Micron's retailer), Elpida, Hynix and Samsung are all top quality.

Rick

Reply

Answer 4

Jun 12, 2012 4:28 PM in response to David Mahony

Remember that your Mac Pro uses Errror correcting Code ECC DIMMs. Installing non-ECC will turn off that excellent feature, and is a Bad Idea.

Most folks who think they got Bad RAM actually got RAM that is perfectly good, but is the Wrong RAM for their machine.

Reply

Answer 5

X423424X

Level 6

14,265 points

Jun 12, 2012 4:31 PM in response to David Mahony

David Mahony wrote:

Thank you for the advice but I'm sure I read somewhere that to utilise the 256 bit addressing then the ram needs to be an equal number of matched pairs in the riser boards (4 x 2gb)????

My info doesn't contradict that. The small print above the picture explicitly says that "must be installed in pairs of identical size and type". But they have to be installed according to that diagram.

Reply

Answer 6

David Mahony Author

Level 1

9 points

Jun 13, 2012 1:51 PM in response to X423424X

Please dont misunderstand I wasn't suggesting that you were - However the diagram just gives examples of how to install but gives no mention of 256 bit addressing or how to achieve the best possible speed other than using the layouts shown.

Because I dont need to take this machine past 8/10Gb of memory for the foreseeable future, I've just purchased 4 x 2 Gb modules.

Ths just leaves me needing some clarification on how best to install them with the 2 remaining 1 Gb modules?

Do you think it would be best as:

Riser Board A:

Dim slot 1 - 2Gb

Dim slot 2 - 2Gb

Dim slot 3 - 1Gb

Dim slot 4 - 1Gb

Riser Board B:

Dim slot 1 - 2Gb

Dim slot 2 - 2Gb

Maniy thanks once again

Reply

Answer 7

David Mahony Author

Level 1

9 points

Jun 13, 2012 1:53 PM in response to Grant Bennet-Alder

Thanks for the advice - Just checked with the supplier and they assured me they were fully buffered and EEC compliant.

Reply

Answer 8

David Mahony Author

Level 1

9 points

Jun 13, 2012 1:55 PM in response to Ricks-

Thanks Rick, the supplier has told me I'll be receiving either Hynix or Samsung - Fingers crossed they do the business!

Reply

Answer 9

The hatter

Level 9

60,980 points

Jun 13, 2012 2:20 PM in response to David Mahony

Barefeats: 2008 showed best memory bandwidth from using all 8 DIMM slots.

2006-7 was best with a set of four (two on each Riser) for quad channel and to reduce latency (and the worst configurations were one or three sets).

If you don't need more than 10GB fine, and room to add more later and get that 17%.

Reply

Answer 10

David Mahony Author

Level 1

9 points

Jun 13, 2012 2:32 PM in response to The hatter

So given that I have only 6 modules to install (4 x 2 Gb + 2 x 1 Gb) I'm unable to fill all 8 slots.

How best would you suggest I install them.

Plead note that I'm not in a position to buy additional ram just I case you ask!!!

Reply

Answer 11

The hatter

Level 9

60,980 points

Jun 13, 2012 2:43 PM in response to David Mahony

just leave as is, you have 2008 and it still works fine and you won't notice except in benchmarks which are only synthetic tests.

Reply