[aafuss]

The iMac G5 Developer Note is now online:
http://developer.apple.com/documenta...section_1.html


Of interest:

FSB- I was reading the iMac G5 developer note and noticed the Education and 17" configurations have a 533 MHz FSB.

Conincidently, this is similar to a PC I'm using right as I type this, that has a P4 2.4GHz with the Intel 82845G IO/Controller and ICH4 southbridge (similar to the Apple U3L and Shasta chipset used in the iMac G5) which has the same FSB as the iMac G5 Education and 17" configurations-533 MHz.
Audio-similar to Intel HD Audio in some ways, but not even as close as good to HD Audio.

[ddma]

The iMac G5 supports Dual Channel if we have a pair of identical memory installed??? That would be a great news!!!

---

Additional DIMMs can be installed. The combined memory of all of the DIMMs installed is configured
as a contiguous array of memory. The throughput of the 400 MHz memory bus is dependent on the
DIMMs installed. If only one DIMM is installed, the memory bus is 64-bit. If two non-identical DIMMs
are installed, there are two 64�Vbit memory buses. If two identical DIMMs are installed, the memory
bus is 128-bit. Identical DIMM pairs have the same size and composition and provide the fastest and
most efficient throughput.

[deboerjo]

Sweet!! It IS dual channel!

And BTW, it's actually faster than the 533MHz bus on a PC, since the PC's "533MHz" is actually 133MHz quad-pumped. The bandwidth of 533MHz, but the latency of 133MHz.

[Simon]

Originally from Apple:
If two identical DIMMs are installed, the memory bus is 128-bit. Identical DIMM pairs have the same size and composition and provide the fastest and most efficient throughput.

Yes! This is great!

So all you need is a pair of identical 1GB DIMMs to get pure happiness.

[H. Georgan]

Question: I ordered a new iMac with a single 512mb card. I plan to fill the second slot with another 512mb bought elsewhere. Will these two chips be considered "matched" in order to have the benfit of dual channel?

[PEHowland]

Originally posted by H. Georgan:
Question: I ordered a new iMac with a single 512mb card. I plan to fill the second slot with another 512mb bought elsewhere. Will these two chips be considered "matched" in order to have the benfit of dual channel?

In the absence of any hard information from Apple, to be safe you would need to ensure that the second chip had the same timings as the memory in the machine (eg. same CL, same RAS-to-CAS delay, etc) as well as the same configuration (eg. 64Mx8). The best way to ensure this is to take the back off the iMac when it arrives, note down the part number for the memory chips used on the DIMM's and then do a Google to find out their specifications. Then, buy 3rd party DIMM's with the same specifications. Just buying "iMac compatible memory" from a 3rd party supplier would not guarantee that the specification was sufficiently similar for the iMac to operate in dual-channel mode.

[H. Georgan]

Thanks!