I have a 2.93 Quad-Core (4.1) Mac Pro. EFI updated to 5.1.
The strangest thing: when I upgrade RAM to fill all slots (4x16) the graphics card freezes at startup. It works with 3 slots filled (48 gig). Why?
At first i though there was something wrong with the RAM (1066 DDR3) – but then I noticed I could access the computer through file sharing – it´s up and running! I´m using the DVI port.
Is this a known problem – what to do?
Mac Pro, OS X Mavericks (10.9.5)
what is your graphics card?
Oh, sorry – it´s a NVIDIA GeForce GT 120.
That is really interesting, because that is the one card that relies solely on Bus Power, and does not require the use of any Aux power cables to function properly.
Could the memory modules be using up too much power, and starving the GT120 for power?
Can you activate screen sharing and make sure that all four memory modules are marked "present"?
Screen sharing don't work when the card is frozen, only file sharing (and probably SSH, but I have not tested (maybe I can check if all RAM is present this way?)). But I guess the power is some kind of clue! I will try to find another card for testing.
Or is it possible to power the card with external power from elsewhere in the computer?
no, the card can't accept power from anywhere else.
I thought I remembered OWC/MacSales limiting you to three @ 16GB in the four-core models. I checked their site, and sure enough, they say only three. Maybe they know something we don't:
.
That's interesting. I don't think I saw that note about a maximum of 3 16GB in a 4-core the last time I looked at Mac Pro RAM there.
It's a timing issue. I lose PCI slot reliability when I populate all 8 slot. If I run 3 slots per CPU, all is great. My 09 has been like this since I bought it new.
Your computer can recognise a maximum of 48G Ram, ie 3x16. So there is no point putting in more and I suppose it is just failing to start in one of several possible ways. You can have 4x4,4x8, 3x16 but clearly not 4x16 installed.
64 gig of RAM kills graphic card...
