[XTTX]

Well I know on paper 800 MHz has a definitive advantage over the transfer rate of the 667 MHz modules, but in reality, does anyone see a noticeable difference in performance.

Also as far as CAS latency, is there any major difference between 4-4-4-12 and 5-5-5-15

Edit: one more thing. As far as pricing goes, do you think now would be a good time to buy the 4GB (2x2) kits seeing as 8GB kits are being released, or do you think that there will be a bigger price drop in a month or two.

[mduell]

No, there is none, because they'll be operated at 667Mhz. The faster timings are pointless for the same reason.
May as well buy now, DDR2 is dirt cheap; as the industry moves to DDR3, DDR2 will become a bit more expensive (just as DDR and SDRAM did), while DDR3 prices will plunge below DDR2 prices.

[Simon]

Originally Posted by XTTX 

Well I know on paper 800 MHz has a definitive advantage over the transfer rate of the 667 MHz modules, but in reality, does anyone see a noticeable difference in performance.

No, it actually doesn't. Becuse it's not the DIMM that sets the speed, it's the chipset. And regardless of Crestline's 800 MHz FSB, its memory interface bus is always 667MHz. 800 MHz DIMMs have exactly zero performance advantage over 667 MHz DIMMs on a Crestline chipset.

On a Penryn MBP you should stick to the PC2-5300 Apple specifies. People have had issues with PC2-6400 on those. On Merom MBPs both work.

Also as far as CAS latency, is there any major difference between 4-4-4-12 and 5-5-5-15

No benchmark done on a Mac has shown any considerable gain due to lower CAS latency. And by considerable I mean more than the error margin of that measurement.

This has all been discussed in detail in this sticky thread BTW.

[Big Mac]

Originally Posted by mduell 

DDR2 will become a bit more expensive (just as DDR and SDRAM did). . .

Did DDR really become more expensive? 3 or so years ago I bought 2x512 PC3200 for my G5 for around $75. A month ago I bought 2x1GB (both name brand, btw) for my G5 for only $60. Perhaps RAM in general has gotten that much cheaper. . . .

[ghporter]

As Simon points out, we've gone into the ins, and outs of laptop RAM in the sticky thread-which is why it was created in the first place.

But Big Mac brings up a good point that would be off topic in the sticky thread. What happens frequently is that the "newest, bestest" kind of RAM gets the manufacturers' attention and they put as much manufacturing capacity as possible into the new stuff at the expense of making the older stuff, so the price goes up.

[Eug]

Originally Posted by Simon

On a Penryn MBP you should stick to the PC2-5300 Apple specifies. People have had issues with PC2-6400 on those. On Merom MBPs both work.

Yep. I bought PC2-6400 for my Penryn MacBook. It did NOT work (as mentioned in Simon's thread). It would seem that some companies do not give the proper SPD timings for slower speed operation.

Why did I buy PC2-6400? At the time it was on sale and it was actually cheaper the than the PC2-5300 RAM.