Is it possible to just put 1 RAM stick in a Mac Pro???

[Morshu9001]

I have a 2008 Mac Pro that randomly failed a couple of days ago. It stopped booting up except off of DVDs, curiously. When I did the Apple Hardware Test, the test did not return anything, but it did say that I have an error in the first slot of the DIMM riser B (the RAM board on the bottom) before I even ran the test. This is a second-hand computer, and I opened it up and realized that I actually have 6GB of RAM (2x2 + 2x1), not 4GB like the system detects! Evidently, the 1GB sticks don't work. They were on riser B.

So I want to remove all the RAM from that riser, but the manual says that I need to put one RAM stick in the first slot of A and the second in the first slot of B if I want to use 2 RAM sticks. But it doesn't mention using 1 RAM stick at all. Can I use just 1 RAM stick or put both sticks on riser A in slots 1 and 2 safely?

 

[chrfr]

But it doesn't mention using 1 RAM stick at all. Can I use just 1 RAM stick or put both sticks on riser A in slots 1 and 2 safely?

The 2008 and earlier machines need pairs.

 

[Morshu9001]

The 2008 and earlier machines need pairs.

Crap. Can I put the entire pair on just one riser instead of putting one chip on each? I doubt it.

 

[JoeG4]

I don't see how anything could go wrong if you try lol

 

[Morshu9001]

I don't see how anything could go wrong if you try lol

I don't either, but I don't know what I don't know about certain things on this computer. Don't want to take unnecessary risks with a $1K machine.

 

[chrfr]

Crap. Can I put the entire pair on just one riser instead of putting one chip on each? I doubt it.

I can't remember, but the riser cards can go in either slot.

EDIT: Try this: http://www.xlr8yourmac.com/tips/Mac_Pro_FBdimm_Pairing.html

You won't damage anything by experimenting with different slots, the RAM just won't be recognized properly.

 

[Morshu9001]

I can't remember, but the riser cards can go in either slot.

EDIT: Try this: http://www.xlr8yourmac.com/tips/Mac_Pro_FBdimm_Pairing.html

You won't damage anything by experimenting with different slots, the RAM just won't be recognized properly.

Yeah, now that I think about it, I already did accidentally try this by putting one of the RAM sticks in slot 4 on the bottom instead of slot 1 by mistake.

I tried swapping the riser cards. B is still bad. In fact, B may have always been bad because it couldn't detect the RAM that was on it. So I'll try putting both on A.

EDIT: Put both on one riser. AHT recognized all 4GB. Computer still won't boot. So now it might be something other than the RAM that is causing this, and riser B and its 2x1GB RAM sticks were just doing nothing the whole time I had this Mac.

 

[Morshu9001]

OK what the heck...
It boots off another Mac that's in Target Disk Mode.
My main bootup drive now has random s*** files that I've never seen before that have nothing meaningful in them, and one of them doesn't even have a name.
My other bootup drive, which appears fine, won't work.
A drive connected with USB won't work as a bootup device (in case it was eSATA-related).