RAM in iMac G5 Revision

Question

I am wondering the following about the new iMac that was announced on the 12th.
The previous iMac manual had the following RAM requirements (in the 'do it yourself' manuals):
About iMac G5 Memory
1. iMac G5 computers work with memory modules (DIMMs) that meet all of these
criteria: PC3200, 2.5V, unbuffered, 8-byte, nonparity, 184-pin, 400Mhz DDR SDRAM.
2. There are two RAM slots. The maximum amount of RAM you can install is 2 GB. You
can use RAM module sizes of 256 MB, 512 MB and 1 GB, in either slot.
3. DIMMs with any of the following features are not supported in the iMac G5 computer:
registers or buffers, PLLs, ECC, parity, or EDO RAM.
I am wondering what the new specifications are. The manuals appear to have been changed to show "Ambient Light Sensor" which I presume means they apply for the new models too. However, the specifications have changed for RAM on the Apple H/W site.
If I purchase RAM with the following specifications (generalised) will it work:
DDR2 SDRAM PC2-4200 at 533mhz non-ecc
That's the closest I could find myself. But I was concerned that there were no manuals and if it were not standard RAM.
Thanks for your assistance,
James

Answer 1

JamesAU:
i 1. iMac G5 computers work with memory modules (DIMMs) that meet all of these criteria: PC3200, 2.5V, unbuffered, 8-byte, nonparity, 184-pin, 400Mhz DDR SDRAM.
Technically that's PC3200 (AKA DDR400) and 200 MHz. The clock fed into a PC3200 module should never be higher than 200 MHz, although hobbyist "overclockers" sometimes try higer frequencies to see if it works. "Marketing speak" refers to a "data rate" of 400 MHz because the data is transferred on both clock edges.
i 3. DIMMs with any of the following features are not supported in the iMac G5 computer:
registers or buffers, PLLs, ECC, parity, or EDO RAM.
Registered output and/or buffers are useful in some cases, but aren't common in personal computing. PLLs would take an incoming clock and produce a more accurate version, or perhaps a faster clock. ECC (error code correction) is generally saved for "mission critical" systems; Data errors are rare in most RAM that's properly rated. EDO (extended data output) DRAM is an outdated asynchronous interface standard. I'm surprised they didn't mention FPM (fast page mode) DRAM.
i DDR2 SDRAM PC2-4200 at 533mhz non-ecc
It's not backwards compatible with PC3200 applications, if that's your question. DDR2 has a slightly different protocol that isn't compatible with a DDR memory controller and the standard module is a 240-pin DIMM. PC3200 comes in 184-pin DIMMs. It's almost tempting because the prices of equivalent sized DDR2 memory are often cheaper.