RAM Question...

Hello Mac People

Allriighttt.... I have a RAM question.. I just bought a G5 (1.8 Ghz) Single Chip, and It came with 2.5 GB of RAM in it... Under the Specs it says:

RAM Type: PC3200 DDR
Min. RAM Speed: 400 MHz
Details: Supports 400 MHz PC3200 DDR SDRAM.


I installed 2 more GB today, and the computer is not recognizing it.. The specs on the RAM i bought are:
Memory Capacity : 2GB
Memory Technology : DDR
PC Rating : PC3200
Computer Type : Desktop PC
Memory Brand : SnT

I learned after reading up on some of these forums that ther eis a difference between MAC ram and PC ram. I am afraid I know the answer to my question, but I wanted to verify it with you guys... Did I buy PC ram for my mac? Thanks for your help!!

-K

You didn't say what model year your G5 is but according to Mac Tracker the 1.8 Ghz model has a maximum memory capacity of 4 Gb. 4 memory slots of which memory must be installed in matched pairs. Which would mean installing 4 each PC-3200 2.5v unbuffered, 8-byte non parity 184 pin DDR SDRAM. You installed 2 Gb added to the already 2.5 Gb, that's not going to work.

I don't know where you got the idea that memory modules for the Mac and PC are different, because they're not. The type of memory and speed will vary for a Mac same as for a PC. Depends on what is specified for that particular machine.

Regards.

just to add... I Tried the Option Command P+R on boot.. If it is true that I am a dumbass and I DID make this mistake (buying the PC ram for the MAC), can anyone link me to a some ram that will work with my comp? Again, thanks guys...

-K

hey chscag,

awesome.. your giving me hope... You are right about the 4 GB Max. I took 2 of the previous ones in there OUT, and replaced them with the ones I bought. I was under the impression that the .5 was (2) 128 MB chips.. So what shall I do here?

The first pair (in the 1 slots) is:
Kingston KVR 400x 64c3a/ 2G
So I am assuming that the pair of these together makes 2 GB.

the second pair (in the 2 slots):
PC3200, 256 MB, DDR, 400x

So I assumed that if I took the 2 256 MB chips out and replaced them with the 2 new 1 GB chips that this would make a total of 4. Is my logic flawed here?

1. There is no difference between RAM for Macs and RAM for Windows computers.
2. So you had 2.5 GB before, and after removing two modules and installing two new ones, you still have 2.5 GB?

If you had mistakenly removed your two existing 1 GB modules and replaced them with your two new 1 GB modules, you would have the exact same amount of RAM. You should double check to make sure you actually removed the 2x128 MB and not the 2x1 GB.

If you have checked and you're absolutely certain that all four GB are in the Mac now, you should try switching them around. If that doesn't work, try booting your machine with only your new RAM and nothing else. If your new RAM isn't working right, it'll fail to boot, and you can send it back for a replacement.

mama,

well, I tryed booting with just the 2 new ones in.. The computer made a vacuum sorta sound, and beeped at me funny. Shoot. Could you possibly tell me the specific RAM i should buy? I have a G5 (powerPC 950fx).. 2004... 1.8 Ghz...

arg.... im confused...the specs say
Details: Supports 400 MHz PC3200 DDR SDRAM.
Standard RAM: 2.5GB
Maximum RAM: 4.0 GB

This is what I bought..
2GB 2 X 1GB PC3200 DDR 400 PC 3200 2700 2100 MEMORY RAM - eBay (item 110330199830 end time Feb-23-09 09:12:08 PST)


awlkdjawkldhawldhaw..


Thanks for your help everyone..
-K

You know, this is weird... technically, that RAM ought to work, and you'd think that sending it back for a replacement would be fine. However, the RAM you got is high-density. That means that the RAM chips are only on one side of the module and have 128 MB per chip. With 8 chips, that equals 1 GB. Your other memory, though, is probably low-density, meaning it has RAM chips on both sides of the module. 16 chips x 64 MB per chip = 1 GB.

Apparently, high-density RAM is usually cheaper but might have trouble working with certain machines. The problem is, I can't find out if it's flat-out incompatible with the G5 or if it's just less likely to work but will work if you get lucky. One discussion on Apple's support site suggested that high-density (128MB per chip) DDR is not JEDEC-compliant, and while most computers are fine with that, a Mac might be a little more fussy.

Personally, I'd say try for a replacement, and if the replacement also doesn't work, see about getting low-density (64 MB per chip, 8 chips on each side) RAM instead.