Which RAM and HD in MBP?

[Timur]

Hey ladies!

I just saw some pictures of the 2 x 1 GB RAM sticks of the new Macbook and identified them as Samung "-HCF8" brand. After some internet search I came to conclusion that these should be fast CL7 (26.3 ns) DDR3 chips and thus have about the same latency performance as CL5 (25 ns) DDR2 ones while providing higher bandwidth.

Does anyone know wether the 2 x 2GB (=4GB) MBPs also use CL7 chips or rather the slower CL8 or CL9 ones?

I'd also like to know which HDs are build into the 320GB 7200 RPM option? Personally I prefer the WD drives at the moment, so I might opt to build in my own if I go for a MBP.

 

[richard.mac]

hey man!

im not sure about the exact specs.

DDR3 definitely has a lower latency than DDR2.

 

[Timur]

hey man!

im not sure about the exact specs.

DDR3 definitely has a lower latency than DDR2.

Thanks, but that's not generally true. DDR2 667 @ CL5 = 25 ns, DDR2 800 @ CL4 = 15 ns (!), DDR3 1066 @ CL7 = 26.3 ns, DDR3 1066 @ CL9 = 33.8 ns (!). And that's only CAS latency.

The primary benefit of DDR3 is the ability to transfer I/O data at eight times the data rate of the memory cells it contains, thus enabling faster bus rates and higher peak throughput than earlier memory technologies. However, there is no corresponding reduction in latency, which is therefore proportionally higher.

 

[richard.mac]

oh, the higher clock speed obviously does something

 

[Timur]

Yes, RAM latencies is advertised in CLOCK cycles (CL5 means CAS Latency is "5 clock cylcles"). When looking at specs they mostly talk about "time in ns" though, which also makes more sense.

A higher clock frequency leads to shorter single cycles. But current DDR3 modules need more of those cycles to work (that's why DDR2 can be bought at cycles downto 4 while DDR3 needs at least 7).

What I want to know is wether Apple builds CL7 or CL9 modules into their top product.