Other MacPro 1,1 only recognises DIMMs in the 1st and 3rd slot only

[Baldung99]

It doesn't matter what DIMMs I use (I have 512MB, 2GB and 4GB DIMMs) or which riser board I plug them in, only the first and third DIMMs ever work, only on whatever riser is in the topmost slot. Otherwise the MacPro acts like it has no memory installed.

How should I go about troubleshooting that? Or better question - how fried is my motherboard?

EDIT: after attacking the slots (all of them, both on the mobo and the DIMM slots) with some canned air, the lower RAM riser started working perfectly. where do I even go from there?

EDIT vol.2: there's now ANOTHER problem. Both RAM risers only work on the bottom slot - but ONE of them recognises two of my 4GB DIMMs as only 2GB ones. I'm confident that this is a fault of a riser since if I transplant the same DIMMs to the 'good' riser they're all recognised properly. I haven't had the issue with the 512MB and 2GB DIMMs.

 

[Lil Chillbil]

Hi there good morning,

Let’s start slow and entertain two troubleshooting questions.

1. Since you stated improvement with canned air, I recommend that you use only enough 99% Isopropyl alcohol to dampen a long high quality cotton swab. Unplug the machine and press the front power button to remove built up energy. Remove both riser cards and clean the physical brass or gold contacts from the riser card to the pcb. Repeat for both cards A and B. Now here’s the dealio, ideally you don’t want to get any alcohol on the ever aging plastic slots. But we want to clean the pins simply by inserting the risers into their slots; with the contacts slightly glistening with alcohol a few (1-3 times) following more careful blowoff with safe electronic duster.

2. Memory timings for the 1,1 and 2,1 can cause some frustration when upgrading RAM on these machines pulled from PC environments and refurbished and sold on eBay. Even if the modules match speed, if the timing is offset my machine refuses to register as a “matched pair”. I had this issue recently.

I’m sorry for quite the late response but I hope this helped