[viji_99]

Hi,

I have an IMAC G5 with 512 MB Ram (Single Stick). I guess the memory type on iMAC is DDR400 SDRAM. I'am getting a good deal for a 256MB RAM pulled out from a Mac mini. But the type of RAM used in Mac Mini appears to be DDR333 SDRAM. I have two questions before I go for this purchase

1. Will DDR333 work with my IMAC G5 (1.8 Ghz)
2. Would there be any performance degrade in pairing 512MB DDR400 RAM with 256MB DDR333 RAM.

Thank you.

[bassplayinMacFiend]

1. No, iMac RAM must be DDR400
2. The iMac will not operate properly without using DDR400 RAM.

[bostongeek]

What is the exact spec of the ram in the new iMac for those wanting to match 3rd party memory?
Doesn't specify what CL the memory in the iMac is...

Learn what kinds of memory you can use with your iMac G5. iMac G5 computers work with memory modules (DIMMs) that meet all of these criteria: PC3200, unbuffered, nonparity, 184-pin, 400Mhz DDR SDRAM. 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. DIMMs with any of the following features are not supported in the iMac G5 computer: registers or buffers, PLLs, ECC, parity, or EDO RAM. Always follow the upgrade instructions for Memory and AirPort Extreme card installation as written. Never attempt to remove screws that are not listed in the upgrade instructions.

[Paul]

You can use Mac mini ram with your iMac, I have a 256 stick paired with my original 256 that came out of a mini. They are both exactly the same type of ram.

[viji_99]

Hi Paul,
Are you talking about iMac G5. When I looked at the memory type used for mac mini & iMac in apple.com they are different as below.

Mac mini - DDR333 SDRAM
iMac G5- DDR400 SDRAM.

Would appreciate yr quick response as I'm supposed to meet the seller in the evening. Thanks.

[Paul]

Yep, iMac G5. I got the rev. A back in October and when the Mac mini was released I bought someone's old 256 stick to "pair" my ram and get the 128 bit bus. You won't be able to "pair" the odd-sized sticks, but it should work fine. Just make sure that the ram coming out of the Mac mini is 400 and not 333. Apple shipped all 400 just to save $ when buying parts in bulk. I don't know if this has changed since January.

[viji_99]

Thanks Paul for the detailed info. How do we check the RAM type (400 or 333?) by looking at it. Also in my case it will be 512+256 so it wouldn't be a "pair". What do you think will be the impact in terms of performance (I belive with this combination the bus width will get reduced)

This is what I see in the picture of the memory stick published.

PC 3200 U - 30331-Z
256MB DDR PC 3200 CL3

[Paul]

iirc PC3200=400 PC2700=333 so you should be all set. and this won't slow your bus at all, it will just stay at the current 64 bit.

[viji_99]

Thatz great. Thank you. Pl. correct me if my understanding is right. With single stick the bus width would always be 64 bit and with two sticks of equal capacity and speed the bus width becomes 128bit. With 2 sticks of different capacity the width will remain at 64bit).

[Paul]

bingo

[Luca]

Some minis come with PC3200 RAM anyway, instead of PC2700. Mine did, as did a sample one evaluated by Anand of AnandTech. You obviously can't guarantee it but there's a small chance you'll get PC3200. Like others have said, if you use PC2700 in a new iMac, it won't work.

[viji_99]

Thanks everyone. I got the memory and just installed it on my iMac. Also verified the model (it is PC 3200!) and speed. It is same as my 512MB stick. Everything works great.

Paul: My special thanks to you for yr quick and precise responses. You are the man and this is a great forum!