Mac Pro 1.1 red light on memory board - help!

Discussion in 'Mac Pro' started by les24preludes, Mar 8, 2016.

  1. les24preludes macrumors member

    Feb 6, 2011
    I have a Mac Pro 1.1 which won't boot properly - it's unstable. The lower memory board shows a red light opposite 03A3, which seems to correspond to DIMM2. I took out the two 1Gb RAMs that were in DIMM 1 and 2 and put in two 512Mb from the upper memory board. Same red light comes on. Does this mean a fault with the actual memory board or riser or what?

    How do I fix this? Thanks for help.
  2. r6mile macrumors 6502

    Feb 3, 2010
    London, UK
    Try shifting the memory modules around, and reseating the risers, etc. I had this with my 3,1 but that fixed it.
  3. les24preludes thread starter macrumors member

    Feb 6, 2011
    Reseated the memory, but no help. I moved the memory board from bottom to top, and the red light went with it. So it looks like it's a problem with the memory riser board, which is OK since I found one from a local Mac repairer I can pick up tonight. So hopefully it's not a logic board problem.
  4. Machines, Mar 8, 2016
    Last edited: Mar 8, 2016

    Machines macrumors 6502


    Jan 23, 2015
    Fox River Valley , Illinois
    I should have anticipated this , as the number one reason back in the day why the Mac Pro 1,1 (2006) , 2,1 (2007) and 3,1 (2008) workstations failed was burned out memory modules . DDR2 FB-DIMM modules are notorious for overheating . So, it seems you either have failed memory modules or a failed memory riser board . Just keep swapping out memory modules (don't worry, there is an endless permutation ;) ) to determine which and use this guide for proper memory installation :

    Start with a minimal configuration of two memory modules and work up from there . Just because a module does not work in one slot, does not mean it won't work in another :p
  5. les24preludes thread starter macrumors member

    Feb 6, 2011
    This is one sick machine. I bought 2 more memory risers and a couple of new 2Gb DIMMs. Played around a bit and eventually the red light went out. However, this has fixed nothing. Still can't load Snow Leopard on a fresh install - hangs half way through. Won't run the OS on the original hard drive either. I think it's going to be a new Mac Pro 4.1 single processor - I can get a decent deal on one. If I have that running I can at least work. Then in time I'll take the MP 1.1 apart and clean it. I'm wasting days looking at the screen showing me a sick computer. I should be working!!

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