How to tell Memory Riser A & B apart (2008 MP)

fridgeymonster3

macrumors 6502
Original poster
Jan 28, 2008
493
13
Philadelphia
I took my early 2008 Mac Pro apart this afternoon to do my annual cleaning and to do some upgrades (see pic). I removed both memory risers without remembering which riser was A and which was B. In the past, if I put the riser back in the opposite way, my Mac Pro refuses to start. I'd rather not have to futz around with the memory risers, can someone tell me how to distinguish the risers from each other?
 

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PowerPCMacMan

macrumors 6502a
Jul 17, 2012
800
0
PowerPC land
Hi, having owned an 08 Mac Pro myself the boards are identical. It does not matter which one is A or B, as both are the same. I suppose you could take a sharpie and write an A for one, B for the other. Just be sure you don't write on a contact.

Best to write it off to the side, near the copyright dates.
 

paulrbeers

macrumors 68040
Dec 17, 2009
3,960
120
My 2006 doesn't care. I assume if it mattered Apple would have differentiated the boards... They are smart like that.
 

snberk103

macrumors 603
Oct 22, 2007
5,503
87
An Island in the Salish Sea
I have the 2008 8 core, and recently needed to swap the A & B risers to diagnose a memory problem. My system didn't care which riser went where.

If your's is being finicky then you may have a bad one. At one point I thought I needed a new one, and found out that they were surprisingly cheap. The store (Apple authorized, not an Apple store) quoted me $100 Canadian for a replacement. Luckily I didn't need it. And by "cheap" I mean by Apple's standards... :)
 

thehimay

macrumors member
Mar 17, 2009
54
1
Toronto, ON, CA
The risers are dictated/named by the ports on the logic board itself. In the current layout you have shown:
'Riser A' is the upper (towards the PCIe slots) riser card slot.
'Riser B' is the lower (towards the case bottom) riser card slot.
 
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Snowshiro

macrumors 6502
Jan 12, 2008
384
4
The risers are dictated/named by the ports on the logic board itself. In the current layout you have shown:
'Riser A' is the upper (towards the PCIe slots) riser card slot.
'Riser B' is the lower (towards the case bottom) riser card slot.
Excactly that. The actual boards that hold the memory are identical. If you slide the board into the top slot, it becomes Riser A. If you slot it into the bottom slot it becomes Riser B. Which way you do it doesn't matter (unless something is faulty).
 

pprior

macrumors 65816
Aug 1, 2007
1,440
8
Wow, I just spray compressed air around in there. Way too much work, imo.

And it doesn't matter - they're the same.
 

Phrygian

macrumors regular
Nov 26, 2011
196
0
i have an early 2008 as well and it is very dusty.... I haven't had the guts to take off the front fan unit.

and you got quite a lot of storage on that, kudos
 

fridgeymonster3

macrumors 6502
Original poster
Jan 28, 2008
493
13
Philadelphia
Thanks for the replies. I thought the Memory boards were interchangeable, I just had a problem one time that was solved by swapping the boards. I didn't have any problem last night when I started my MP back up.