Upgrading MBP SR RAM - 800 vs 667

Quick question:

I'm looking to upgrade my MBP Santa Rosa's RAM. I currently have 2 gigs of DDR2 667 MHz RAM - would it benefit me at all to go to 800 MHz RAM, or should I just stick with 667? And if it would benefit me, would it only work if both modules were 800 MHz?

 

It will get downclocked to 667mhz, so unless the 800mhz RAM is cheaper, get the 667mhz PC5300 ones. The current Intel motherboards, though the CPU is 800mhz, can only support 667mhz RAM.

 

Ahh okay, thanks! The 667 is cheaper, I can get a 2 gig module for 98 dollars. Does it matter than I'll have 3 gigs, for 32-bit XP and Tiger/Leopard?

 

Depending on what you're doing, 3GB may end up being slower than 2GB. When you move to 3GB, you loose dual channel support, and hence a lot of speed. The only case which the 3GB would be worth the money would be if you're doing a lot of work with huge files(1gb and up). Now, if you could get two 2GB sticks, that'd be sweet.

 

Ohhh, really? Interesting - I'd heard somewhere that dual-channel support provided pretty negligible gains, but I guess that isn't the case. In that case I'll just get 4 gigs at some point. Will I really see a performance increase in Tiger or XP 32-bit with 4 gigs though? I heard they can't recognize a full 4 gigs.

 

4gbs would be fine with OSX since its already a 64 bit OS i believe. For windows you would have to use 64-bit XP or Vista.

 

OSX doesn't recognize that much ram. Neither does XP (neither the 32 or 64 bit versions). Leopard and Vista can recognize the 4 gigs though.

 

Tiger does recognize that much RAM. And with the newest incarnation of the Macbook Pro, the architecture is not an issue either. So yes, this machine can run 4GB of RAM.

 

Yes, Tiger recognizes 4 GB of RAM.

 

as far as i know, not all versions of vista will, i think its just the 64 bit versions.

 

Dual channel has its advantages sometiems and is useless in other circumstances. If the RAM frequency is the same as the FSB, there is no need to use dual channel. However, since the RAM cannot be set at the same frequency as the FSB in the Santa Rosa platform, a bottleneck may occur when not using dual channel. This bottleneck, however, will only occur when the processor is under a heavy load and is requesting the maximum possible data it can from the memory. As such, the memory will bottleneck the processor.

Using different density modules will mean that dual channel will still be active, but its bandwidth will be reduced. It will run in assymetrical mode, and not in "true" dual channel.

 

I guess this is the $64,000 question then: for playing games in Windows XP 32-bit, would it make any sense to go to 3 GB of RAM, or should I just get 4 - and if so, should I wait until I get Vista (will I need 64-bit Vista?) to get the maximum effect?

 

Only 64-bit OSes can read 4 GB RAM, so if you just use 32-bit OSes just get 3 GB. If you use 64-bit Vista, then get 4 GB (if you can afford it ).

 

Thanks for all your help with this issue guys - this is why I love NBR.

I can't currently upgrade to a 64-bit operating system because, for some reason, some necessary software to get on the network at my college can't run on a 64-bit OS. So I'm stuck with my 32-bit XP right now.

If I get 4 gigs of memory, will I still see a performance increase in Windows, even though it can only read 3? Or will it not treat it as 2 modules of 2 gig RAM and then I'd lose that dual-channel support still?