[Lateralus]

I've noticed that even though the system bus of the new Santa Rosa MacBooks is 800MHz, Apple is still shipping the notebooks with 667MHz DDR2 even though 800MHz is readily available.

Is there any reason to NOT buy 800MHz memory if you're planning on upgrading?

[Simon]

First, the new MBs are not part of the Santa Rosa platform (and hence no Centrino badge). They have a Crestline chipset (which happens to be one of three requirements for the SR platform).

The FSB consist of the Processor Interface Bus (between CPU and northbridge) and the Memory Interface Bus (between RAM and northdridge). The Crestline chipset has an 800 MHz FSB (with an 800 MHz PIB), but that doesn't mean the northbridge has an 800 MHz link to memory. Actually the MIB in your MB(P) runs at 667 MHz, so there's no benefit from using 800 MHz memory. Of course it will still work, but it will run at 667 MHz just as if you had bought 667 MHz memory. Bottom line: unless 800 MHz memory is cheaper there's no reason not to use 667 MHz memory in your MB(P).

[PhrogDriver]

Why would Apple not run everything at 800 MHz if it was possible? Wouldn't that increase the overall performance by being able to use the faster RAM?

[Simon]

Originally Posted by PhrogDriver 

Why would Apple not run everything at 800 MHz if it was possible?

It is not possible. The Intel Mobile Express GM965 (MB) and PM965 (MBP, iM) chipsets don't support an 800 MHz MIB. The chipsets support DDR2 memory clocked at either 533 or 667 MHz. You can put 800 MHz memory in there and it will work, but it will not run at more than 667 MHz.

This is not something Apple can change on its own. Intel needs to do it and they will: their next mobile chipset (Cantiga) will come with support for 800 MHz DDR3 memory. It will be launched with the Montevina platform in 2Q08. Cantiga will also have a 1067 MHz FSB rather than Crestline's 800 MHz. And again, the FSB and with it the PIB will be clocked higher than the MIB.

[PhrogDriver]

OK, that makes sense to me now. Thank you for explaining that.

[mduell]

The only reason to buy 800Mhz DDR2 for a MacBook is because you happened to find it was cheaper than 667Mhz DDR2 (I've seen it for desktops, so I wouldn't be surprised if the same happened for laptops). It doesn't add any future proofing (being able to reuse your RAM in the next Mac) because Intel won't go to 800Mhz RAM until they go to DDR3, due to power/heat.

[Simon]

Originally Posted by PhrogDriver 

OK, that makes sense to me now. Thank you for explaining that.

You're very welcome.

[Nivag]

Another thanks from me too!!

[slugslugslug]

Well, while we're on the subject of MacBook RAM, is there any reason not to trust the brands G.SKILL or A-Open, which seem like the best deals on NewEgg for 2- or 4-GB kits?

[Lateralus]

Not sure about A-Open, but G.SKILL seems to have done a good job of quickly establishing a pretty solid reputation.

Assuming you meant A-Data, the same can be said of them as can be said of G.SKILL.

[mduell]

Anything with a 4 or 5-egg rating and >10 votes is fine, IMO.

[slugslugslug]

Originally Posted by Lateralus 

Not sure about A-Open, but G.SKILL seems to have done a good job of quickly establishing a pretty solid reputation.

Assuming you meant A-Data, the same can be said of them as can be said of G.SKILL.

Oh, yup. I did mean A-Data.

Cool. I'm gonna go order me 6 gigs of RAM for 2 MacBooks. (The wife probably doesn't realize that she does need 2 or that I don't really need 4, but I figure I may as well max mine out right when I get it, since prices are reasonable these days..) Thanks, y'all.

[beto84]

Originally Posted by Simon 

First, the new MBs are not part of the Santa Rosa platform (and hence no Centrino badge). They have a Crestline chipset (which happens to be one of three requirements for the SR platform).

The FSB consist of the Processor Interface Bus (between CPU and northbridge) and the Memory Interface Bus (between RAM and northdridge). The Crestline chipset has an 800 MHz FSB (with an 800 MHz PIB), but that doesn't mean the northbridge has an 800 MHz link to memory. Actually the MIB in your MB(P) runs at 667 MHz, so there's no benefit from using 800 MHz memory. Of course it will still work, but it will run at 667 MHz just as if you had bought 667 MHz memory. Bottom line: unless 800 MHz memory is cheaper there's no reason not to use 667 MHz memory in your MB(P).

I am buying a Macbook Pro 2.4Ghz soon, I would like to know if this 4gb kit will work with it? It's 800 Mhz but is actually cheaper than the 667 Mhz kit.

http://www.amazon.com/4GB-Kit-800MHZ...5132720&sr=8-3

Please let me know asap... Thanks!!

[slugslugslug]

Originally Posted by beto84 

I am buying a Macbook Pro 2.4Ghz soon, I would like to know if this 4gb kit will work with it? It's 800 Mhz but is actually cheaper than the 667 Mhz kit.

http://www.amazon.com/4GB-Kit-800MHZ...5132720&sr=8-3

Please let me know asap... Thanks!!

You can do better than that for the 667 MHz SO-DIMMS on newegg.

[beto84]

Originally Posted by slugslugslug 

You can do better than that for the 667 MHz SO-DIMMS on newegg.

I cant buy from newegg as they do not accept international credit cards. Only a few resellers accept them, Amazon is one of them.

All I need to know is if these will work even throttled back to 667 Mhz.....

[slugslugslug]

Originally Posted by beto84 

I cant buy from newegg as they do not accept international credit cards. Only a few resellers accept them, Amazon is one of them.

All I need to know is if these will work even throttled back to 667 Mhz.....

Ah, sorry. Well, from everything I've heard, you can use the faster RAM and it will just run at the chipset's lower speed (see Simon's first response to the OP).

If you're patient I'm sure Simon, mduell, or another of the more encyclopedic members will pop in here to confirm or correct my statement.

[mduell]

Originally Posted by beto84 

I am buying a Macbook Pro 2.4Ghz soon, I would like to know if this 4gb kit will work with it? It's 800 Mhz but is actually cheaper than the 667 Mhz kit.

Amazon.com: 4GB Kit 800MHZ DDR2 Sodimm: Electronics

Please let me know asap... Thanks!!

Originally Posted by beto84 

I cant buy from newegg as they do not accept international credit cards. Only a few resellers accept them, Amazon is one of them.

All I need to know is if these will work even throttled back to 667 Mhz.....

Yes it will work (although the price is about $40 high), but Shipping: Currently, item can be shipped only within the U.S. and the seller is brand new/has no rating (questionable).

[kerosen]

I am a "switcher", I am going to buy a MacBook during the coming days. I was studying your forum and of course I found answers to many of my questions already.
I am not sure that in the Mac world some things are similar like in the PC world but I had this question in mind when I was looking for a Mac as well.
In the "PC world" the answer is that: FSB for the intel core 2 duo is always 4 x system clock. That means system clock is 200 mhz. For a DDR2 (dual channel)the speed is 2 x system clock.
The condition is DDR2/2 >= system clock, which is the case (333 > 200). So, in theory, you might use DDR2 at 400 or 500 and it will stil do the job.
The CPU freq is n x system clock, where n, in the pc world, is a multiplication factor set in bios. For 2ghz system with a FSB of 800, n=10.

This forum is great, thanks everyone
K.

[mduell]

Originally Posted by kerosen 

I am a "switcher", I am going to buy a MacBook during the coming days. I was studying your forum and of course I found answers to many of my questions already.
I am not sure that in the Mac world some things are similar like in the PC world but I had this question in mind when I was looking for a Mac as well.
In the "PC world" the answer is that: FSB for the intel core 2 duo is always 4 x system clock. That means system clock is 200 mhz. For a DDR2 (dual channel)the speed is 2 x system clock.
The condition is DDR2/2 >= system clock, which is the case (333 > 200). So, in theory, you might use DDR2 at 400 or 500 and it will stil do the job.

A little knowledge is a dangerous thing. The Crestline chipset used in the current MacBooks only supports 667Mhz and 533Mhz DDR2, nothing slower. Also, going down to even 533Mhz will hurt performance, particularly graphics performance, due to the reduced memory bandwidth available.

[kerosen]

I mentioned that my explanation is from the pc world. It was just to give an idea about the link between ram speed, system clock, processor speed.
Little knowledge is better than ignorance, anyway.