MP 7,1 RAM Upgrade - I’m Confused

[SayCheese]

I’ve read some of the previous RAM upgrade threads but I’m still confused on what’s recommended for upgrading from base spec on the 7,1.

I’ve got the 4x 8GB sticks and want to add more. Am I right in thinking that 6 sticks is best for performance? I know I need to install in pairs.

I could afford to buy either 2x 8GB or 2x 16GB but no more at the moment. But will putting 2x 16GB in with the original 4x 8GB cause problems?
Also will it cause problems if I then add more 8 or 16 sticks at a later date?

 

[codehead1]

The math is simple. You have to add in pairs, as you know. Then, literally, bandwidth for two sticks is one-third, four sticks is two-thirds, six sticks is 100%.

If you add 2 x 16 GB, you are six sticks wide for half of the memory space, four sticks wide for the other half. Not perfect, but better. Memory speed isn't everything—caching makes up for a lot, and depends on exactly what you're asking of the processor, you're not always keeping memory busy. I think a lot of people won't like this arrangement—it's not ideal—but it's not horrible, especially if you figure on picking up another 4 x 16 GB later, maybe cheaper.

Adding 2 x 8 GB is good, but only gets you to 48 GB. Maybe enough for now, but not expansive. I know I was getting uptown the 32 GB utilized area, and even slightly over, in the early days of running my new MP with 4x8 base.

I bought 6 x 16 GB and sold my 4 x 8 GB. If you get good prices, you could instead buy 8 x 8 GBs second-hand and probably have your 96 GB a little cheaper than the route I took. But not a huge difference and less flexibility for upgrading down the line.

 

[flowrider]

It really is not tough to understand. If you want peak performance:

To get the most out of your new Mac run only six or twelve Dimms. If six, all should be matching. If twelve all twelve should be matching or six should be matching and the other six should match each other. Any other congifuration will suffer a speed penalty.

Lou

 

[DFP1989]

I considered buying eight preowned 8GB sticks on eBay (pulled from new 7,1s), but doing the maths (based on selling prices) I could purchase a 96GB kit (6x16GB) kit for only a few hundred more after selling the original 32GB. I don’t expect to need more than 96GB for a very long time, but at least it keeps the options open.

 

[SayCheese]

Thanks for the help. I've gone for 2x 8GB for the moment on top of the 32 already in there. Hopefully it'll also help by increasing the bandwidth too.