RAM Issue Mac Pro.

[ilegal31]

Hello,


I have an issue with my mac pro's ram, I have a 16GB kit that I had purchased and installed running fine, today I had removed 8GB off the 16GB kit but the computer does not start the computer's front power light just flickers. But, if I put back the all the 16GB kit the computer starts fine, any idea what's going on?.


Thanks in advance.

 

[DanielCoffey]

What model of MP do you have? Different models have different requirements for slots to be populated.

EDIT : Here's the list... http://support.apple.com/kb/ht4433

 

[flowrider]

What model, what RAM slots, and what are the RAM's specs? Need facts to answer questions.

Lou

 

[DeltaMac]

... I have a 16GB kit that I had purchased and installed running fine, today I had removed 8GB off the 16GB kit but the computer does not start the computer's front power light just flickers. But, if I put back the all the 16GB kit the computer starts fine, any idea what's going on?.
...

Any particular reason that you want to remove some RAM?
Most folks would want more

Absolutely, if you add or remove RAM, you need to make sure that RAM pairs are installed properly.

 

[ilegal31]

Hello,


Thanks for the responses, I have a Mac Pro 2,1 dual quad core 3.0Ghz. I had removed the ram to test them on another machine "Works fine", this are the ram specs:

http://www.ebay.com/itm/16GB-4X4GB-...OVED-MEMORY-/161166610758?hash=item2586475146

I just find weird that I have to install all the modules to work, since 4GB of ram is enough to run the computer, I am using 4 slots, the other 4 are empty.


Thanks to all of you for the time taken to provide the responses.

 

[DeltaMac]

You have 2 pair of sticks. Each pair is in slots 1 & 2 of each riser.
If you remove one pair, then you can still run with one pair in slots 1 & 2 of riser A, which is the upper riser.
Probably won't run with only one pair in the bottom riser (Riser B).

 

[ilegal31]

Hello DeltaMac,


I have the 16GB on the lower riser, I had tried also on the upper riser with, 4,8,12 and 16GB ram configuration, I get the same issue.

I have my computer for several years, and also replaced the ram a few times with no issue, this time I jus don't know what the issue could be, I don't think the ram is the issue since is working fine and all the modules are recognized by the machine.


I appreciate your time and response.

 

[DeltaMac]

So, are you saying that RAM won't work in that one (upper) riser, only good in the lower?

The memory risers are interchangeable.
Is there any difference if you swap risers, upper for lower?

Does your Memory Slot Utility report any problem at all?
If you don't know about that utility, it's in the /System/Library/CoreServices folder.
It may not report any problems, but might give you a recommended slot configuration for best performance.

 

[ilegal31]

DeltaMac,


When I try to run Memory Slot Utility , I get this error: Memory Slot Utility is not meant to run on this system. I had tried both raisers, both run the 16GB ram but if I uninstall one of the 4 modules the computer does not start.

 

[DeltaMac]

If you mean that you simply remove one stick, but leave three in place on one riser, then that will not work. It won't start with that configuration. The sticks have to be installed in identical size pairs - 3 on one riser won't do it.
So, should be one pair in slots 1 & 2, on each riser.