New Mac Pro - 4th memory slot

[voyager77]

I just got a new mac pro with 12 Gb of ram.
This means the 4th memory slot is empty and wanting to be filled asap.

Now what fits in there best?
Of course it has to be the same type that's in the other slots, so i'll be going with the Apple stuff.

But does it have to be a 4 Gb module, or can i put in an 8 Gb or even a 16?
Are there any downsides to not having "paired" slots?

 

[Demigod Mac]

Put a matching module in the 4th slot for quad-channel speed.
Doesn't have to be Apple-branded, so long as the specs match Apple's.

http://www.newegg.com/Product/Product.aspx?Item=N82E16820148777

 

[bxs]

I just got a new mac pro with 12 Gb of ram.
This means the 4th memory slot is empty and wanting to be filled asap.

Now what fits in there best?
Of course it has to be the same type that's in the other slots, so i'll be going with the Apple stuff.

But does it have to be a 4 Gb module, or can i put in an 8 Gb or even a 16?
Are there any downsides to not having "paired" slots?

You can install a 4GB or an 8GB spec-matching module in that 4th slot. However, you cannot and must not mix 4 and 8GB modules with 16 and 32GB modules.

Pull up the About This Mac and select the Memory tab for an explanation and/or goto http://support.apple.com/en-us/HT202892

 

[h9826790]

I think it's not the matter of RAM size, but the spec. If there is a 32G 1866 UDIMM ECC DDR3, you may use it with the 4G 1866 UDIMM ECC DDR3 RAM without any trouble.

The real problem is that the 32G stick is RDIMM at this moment. And mixing UDIMM with RDIMM will crash the system.

 

[mintakax]

I think it's not the matter of RAM size, but the spec. ...........

That's what she said