MP 3,1 with 64GB - did I get the wrong kind of sticks?

[pullman]

I just received 8x8GB sticks for my Mac Pro 3,1 from Dr Memory in the UK. I bought these on eBay and here's how they look:

The computer won't boot with 8x8GB installed and all four red LED burn on both risers.

I can of course return them but want to be sure if they sent me the wrong kind. In this thread I saw that the required specs 2RX4 PC2 5300F but mine are 4RX4. It seems unlikely that all eight are broken so I guess I received the wrong kind, but it would be nice to know.


A related question - my 3,1 says the following on the Memory tab. Isn't it weird that it says 667 MHz?? This is with two 800 MHz sticks installed plus 4 of the 667 MHz sticks.

 

[Pressure]

Yes, you need 2 rank FBDIMM (2RX4).

 

[pullman]

Yes, you need 2 rank FBDIMM (2RX4).

Thanks for the quick reply. Ok, I'll return them.

Any idea about the second question?

 

[Pressure]

Thanks for the quick reply. Ok, I'll return them.

Any idea about the second question?

If you mix memory with different speeds it will downclock all modules to the slowest one.

 

[pullman]

Ah thank you, and for replying so quickly.

If you mix memory with different speeds it will downclock all modules to the slowest one.

 

[theone29]

And correct me if I'm wrong but you can only use 56GB max on a 3,1. I bought the wrong ones too, the 3,1 needs a 2Rx4. I bought 8x8GB but only used 6 of 8 and ordered 2 additional 4GB to fill the last 2 slots.

 

[pullman]

Yes I saw that too, something to do with bottlenecking the drives.

And correct me if I'm wrong but you can only use 56GB max on a 3,1. I bought the wrong ones too, the 3,1 needs a 2Rx4. I bought 8x8GB but only used 6 of 8 and ordered 2 additional 4GB to fill the last 2 slots.

 

[AlexMaximus]

Yes I saw that too, something to do with bottlenecking the drives.

I think thats what you are looking for...

http://www.transintl.com/memory/mac-pro-memory/mac-pro-early-2008-with-8-memory-slots.html

or this

http://www.maxupgrades.com/istore//index.cfm?fuseaction=category.display&category_ID=314

together with this

http://www.maxupgrades.com/istore/index.cfm?fuseaction=product.display&product_ID=174&ParentCat=408