MacPro : memory population problem

[UltraNEO*]

Hiya there, a question for those power users....

Today I attempted to upgrade my MacPro from the default 2Gb of Ram with an additional 8Gb of ram. The New modules have been added to banks 2 and 3, the original memory is still in bank1. However the system refuse to see all! Instead i get the following....

Set A
Dimm 1 : 1Gb (original)
Dimm 2 : 2Gb (new)
Dimm 3 : 2Gb (new)
Dimm 4 : 0Gb (empty)

Set B
Dimm 1 : 1Gb (original)
Dimm 2 : 2Gb (new)
Dimm 3 : 2Gb (new)
Dimm 4 : 0Gb (empty)

Total shown is 6Gb RAM

After a reshuffle....

Set A
Dimm 1 : 2Gb (new)
Dimm 2 : 2Gb (new)
Dimm 3 : 1Gb (original)
Dimm 4 : 0Gb (empty)

Set B
Dimm 1 : 2Gb (new)
Dimm 2 : 2Gb (new)
Dimm 3 : 1Gb (original)
Dimm 4 : 0Gb (empty)

Total shown is 8Gb RAM

Another tweak...

Set A
Dimm 1 : 2Gb (new)
Dimm 2 : 2Gb (new)
Dimm 3 : 0Gb (empty)
Dimm 4 : 1Gb (original)

Set B
Dimm 1 : 2Gb (new)
Dimm 2 : 2Gb (new)
Dimm 3 : 0Gb (empty)
Dimm 4 : 1Gb (original)

Total shown is 8Gb RAM



After yet another reshuffle....


Set A
Dimm 1 : 2Gb (new)
Dimm 2 : 1Gb (original)
Dimm 3 : 2Gb (new)
Dimm 4 : 0Gb (empty)

Set B
Dimm 1 : 2Gb (new)
Dimm 2 : 1Gb (original)
Dimm 3 : 2Gb (new)
Dimm 4 : 0Gb (empty)

Total shown is 8Gb RAM

After yet another reshuffle....

Set A
Dimm 1 : 2Gb (new)
Dimm 2 : 0Gb (empty)
Dimm 3 : 2Gb (new)
Dimm 4 : 1Gb (original)

Set B
Dimm 1 : 2Gb (new)
Dimm 2 : 0Gb (empty)
Dimm 3 : 2Gb (new)
Dimm 4 : 1Gb (original)

Total shown is 8Gb RAM

....I give up!


Is it not possible to get the system to see all 10Gb? It seems odd because the system seems to work with 2Gb in as default.. then doesn't allow me to fill in three outta four slots in each bank... What's going on? Can someone shed some light on this?

I'm using the MacPro 2008, Harpertown

Thanks You in advance.

 

[Umbongo]

Set A
Dimm 1 : 2Gb (new)
Dimm 2 : 2Gb (new)
Dimm 3 : 1Gb (original)
Dimm 4 : 1Gb (original)

Set B
Dimm 1 : 2Gb (new)
Dimm 2 : 2Gb (new)
Dimm 3 : 0Gb (empty)
Dimm 4 : 0Gb (empty)

 

[DualShock]

Hiya there, a question for those power users....

Today I attempted to upgrade my MacPro from the default 2Gb of Ram with an additional 8Gb of ram. The New modules have been added to banks 2 and 3, the original memory is still in bank1. However the system refuse to see all! Instead i get the following....

Set A
Dimm 1 : 1Gb (original)
Dimm 2 : 2Gb (new)
Dimm 3 : 2Gb (new)
Dimm 4 : 0Gb (empty)

Set B
Dimm 1 : 1Gb (original)
Dimm 2 : 2Gb (new)
Dimm 3 : 2Gb (new)
Dimm 4 : 0Gb (empty)

Total shown is 6Gb RAM

After a reshuffle....

Set A
Dimm 1 : 2Gb (new)
Dimm 2 : 2Gb (new)
Dimm 3 : 1Gb (original)
Dimm 4 : 0Gb (empty)

Set B
Dimm 1 : 2Gb (new)
Dimm 2 : 2Gb (new)
Dimm 3 : 1Gb (original)
Dimm 4 : 0Gb (empty)

Total shown is 8Gb RAM

Another tweak...

Set A
Dimm 1 : 2Gb (new)
Dimm 2 : 2Gb (new)
Dimm 3 : 0Gb (empty)
Dimm 4 : 1Gb (original)

Set B
Dimm 1 : 2Gb (new)
Dimm 2 : 2Gb (new)
Dimm 3 : 0Gb (empty)
Dimm 4 : 1Gb (original)

Total shown is 8Gb RAM



After yet another reshuffle....


Set A
Dimm 1 : 2Gb (new)
Dimm 2 : 1Gb (original)
Dimm 3 : 2Gb (new)
Dimm 4 : 0Gb (empty)

Set B
Dimm 1 : 2Gb (new)
Dimm 2 : 1Gb (original)
Dimm 3 : 2Gb (new)
Dimm 4 : 0Gb (empty)

Total shown is 8Gb RAM

After yet another reshuffle....

Set A
Dimm 1 : 2Gb (new)
Dimm 2 : 0Gb (empty)
Dimm 3 : 2Gb (new)
Dimm 4 : 1Gb (original)

Set B
Dimm 1 : 2Gb (new)
Dimm 2 : 0Gb (empty)
Dimm 3 : 2Gb (new)
Dimm 4 : 1Gb (original)

Total shown is 8Gb RAM

....I give up!


Is it not possible to get the system to see all 10Gb? It seems odd because the system seems to work with 2Gb in as default.. then doesn't allow me to fill in three outta four slots in each bank... What's going on? Can someone shed some light on this?

I'm using the MacPro 2008, Harpertown

Thanks You in advance.

See pg 44 of this manual:
http://manuals.info.apple.com/en/Mac_Pro_Early_2008.pdf

Note: The memory population rules are different for the 2006/2007 Mac Pro's.

 

[Graeme43]

in mine i have 2 ram in each of the furthest away slots. i think the mac pro works like this

first 2 sticks go top slots at the rear
second 2 go at bottom rear
third 2 go on the top near
fourth 2 go on the bottom near

 

[UltraNEO*]

Sorted... Thanks for your help guys.
I would read the manual but mine's all in Japanese!!

 

[Umbongo]

Sorted... Thanks for your help guys.
I would read the manual but mine's all in Japanese!!

http://support.apple.com/manuals/#macpro

 

[ThirteenXIII]

in mine i have 2 ram in each of the furthest away slots. i think the mac pro works like this

first 2 sticks go top slots at the rear
second 2 go at bottom rear
third 2 go on the top near
fourth 2 go on the bottom near

opposite. reverse that.

it goes A1&2 B1&2 ...then.... A3&4 B3&4 etc.


the screen shot of the users new placement is the ideal solution.

 

[CanadaRAM]

Actually, not quite ideal. If the 2 GB modules were in slots A1 A2 B1 B2, then the machine could do 256 bit access. The smallest RAM should be relegated to the 3 & 4 slots.

 

[UltraNEO*]

Actually, not quite ideal. If the 2 GB modules were in slots A1 A2 B1 B2, then the machine could do 256 bit access. The smallest RAM should be relegated to the 3 & 4 slots.

The original and default location for ram, when the system arrived was in A1 and B1... so I just assumed the new modules would go in A2 and B2 blah... but that's not the case...

LOL... Who would of thought?

 

[Umbongo]

The original and default location for ram, when the system arrived was in A1 and B1... so I just assumed the new modules would go in A2 and B2 blah... but that's not the case...

LOL... Who would of thought?

Yes, it can be confusing without documentation. Memory on FB-DIMM based systems is meant to be in pairs, but with the 5400 chipset when only using 2 DIMMs optimal performance can be gained by putting them on seperate risers.