Dual 2.0 G5 won't recognize memory

[Daringescape]

Ok here's the deal: I have a dual 2GHz G5, I just added another Gig of RAM to the 512 MB that comes installed. When I turn on the machine and check it, there is only 1 GB listed. I checked to make sure the chips were in the right spot and seated correctly. When I click the more info box in the about this mac window, it is only recognizing my two 512 chips as 256 chips. The ram is kingston pc3200 cl3 RAM. Can anyone help me out here?

[Blue Velvet]

Where did you get the RAM and did you specify it yourself?

[Daringescape]

The RAM came from another apple machine - it worked in that one.

[yellow]

I'm NOT a RAM expert, but I can tell you from experience that on older Macs (G3 Powerbooks specifically), when you only see 1/2 of the size of a stick, it means the RAM is not the correct RAM for the hardware. Beyond that, I cannot offer any practical advice.. sorry!

[Blue Velvet]

Our 3 x 2.5 G5s were picky about the RAM that went into them.

Not one of the first batch that arrived (12 sticks), worked. Crucial sent new ones the next day which worked perfectly. The only difference between the 2 was something to do with the CL no.

[HiRez]

Blue Velvet is right, Macs are very picky about their RAM, it has to be exact. For a dual 2.0 GHz G5 tower, you need:

1. PC 3200 (400 MHz DDR) RAM
2. 184 Pin
3. CAS 3.0 Latency
4. Unbuffered
5. Non-ECC
6. 2.5v/2.6v (voltage)
7. Must be installed in matched pairs

You also have to make sure the pairs of sticks are installed in the right slots. You install them in the next available slots (one in each bank) going outward from the center, like this:

BANK 1 SLOT 4 (G)
BANK 1 SLOT 3 (E)
BANK 1 SLOT 2 (C)
BANK 1 SLOT 1 (A)
---------------------
BANK 2 SLOT 1 (B)
BANK 2 SLOT 2 (D)
BANK 2 SLOT 3 (F)
BANK 2 SLOT 4 (H)

Your G5 should come with slots I've labeled A and B here filled. So your next two sticks would go into C and D, the next pair in E and F, and finally G and H.

[Daringescape]

Blue Velvet is right, Macs are very picky about their RAM, it has to be exact. For a dual 2.0 GHz G5 tower, you need:

1. PC 3200 (400 MHz DDR) RAM
2. 184 Pin
3. CAS 3.0 Latency
4. Unbuffered
5. Non-ECC
6. 2.5v/2.6v (voltage)
7. Must be installed in matched pairs

You also have to make sure the pairs of sticks are installed in the right slots. You install them in the next available slots (one in each bank) going outward from the center, like this:

BANK 1 SLOT 4 (G)
BANK 1 SLOT 3 (E)
BANK 1 SLOT 2 (C)
BANK 1 SLOT 1 (A)
---------------------
BANK 2 SLOT 1 (B)
BANK 2 SLOT 2 (D)
BANK 2 SLOT 3 (F)
BANK 2 SLOT 4 (H)

Your G5 should come with slots I've labeled A and B here filled. So your next two sticks would go into C and D, the next pair in E and F, and finally G and H.

That's exactly how I have it installed. As far as the specs go, this ram was in another G5 (dual 2.5 I think) before it was given to me. I just don't understand why it recognizes it, just not at the correct size. Will leaving the RAM in my tower damage it, or decrease performance?

[bankshot]

This report from Macintouch may shed some light on the issue:

http://www.macintouch.com/badram04.html#mar30

[HiRez]

Well if it previously worked in a 2.5 G5, that is odd. First I would check your RAM with the Rember (http://www.kelleycomputing.net:16080/rember/) utility. Then I would try removing the original Apple RAM and move your two new 512 sticks where they were. Then I would try sacrificial chicken blood and tribal dance. :cool: