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You are here: MacNN Forums > Hardware - Troubleshooting and Discussion > Mac Desktops > g5 16 gig memory?

g5 16 gig memory?
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bradleykavin
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Sep 11, 2004, 12:38 AM
 
Hi..if i were to put 2 gigabite memory cards in my g5 instead of 1 gigabite memory cards, could the computer run on 16 gigs of memory? since i have the rev b dual 1.8...could i put four 2 gig cards in my computer and have 8 gigs of ram? although there arent 4 dimm slots, the computer can handle up to 8 gigs of ram (i heard it can also handle 16) ...?
Powermac G5, Dual 1.8 8x superdrive, 250 gig startup drive 80 gig seconday drive, nvidia 6800 gt, logitech z-5500
     
d.fine
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Sep 11, 2004, 04:10 AM
 
Why would you want 16 GB of DDR RAM in your G5 ? Isn't that a little over the top, and completely useless ? Most apps dont read beyond 2 GB ... (based on what I've read here on MacNN)

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mjankor
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Sep 11, 2004, 04:13 AM
 
I'm pretty certain you can and OS X will recognise all the memory. However i doubt Apple supports it and you'd want to be certain that the memory is good to use with Mac's.

The memory controller in G5's supports 48bit (i think) addressing. That something like 32TB of memory so I don't think there'd be a problem there.

So yes I am pretty certain that for a ridiculous price 4 slot G5's can support 8GB and 8 slots can support 16GB.

Of course I could also be very wrong. I suggest just trying it first.
     
discstickers
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Sep 11, 2004, 09:19 AM
 
Originally posted by d.fine:
Why would you want 16 GB of DDR RAM in your G5 ? Isn't that a little over the top, and completely useless ? Most apps dont read beyond 2 GB ... (based on what I've read here on MacNN)
In 10.3, no app can use more than 2GB. Each program is given a 32-bit virtual address space. In 10.4, you can compile it so that the app will receive a bigger address space, but I don't know the limit (I doubt it's 42 though).
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OreoCookie
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Sep 11, 2004, 11:00 AM
 
Originally posted by discstickers:
In 10.3, no app can use more than 2GB. Each program is given a 32-bit virtual address space. In 10.4, you can compile it so that the app will receive a bigger address space, but I don't know the limit (I doubt it's 42 though).
Well, it doesn't matter. BFS (file system of BeOS supported full 64 bit addressing. I don't think it makes much difference to implement even though you will probably stay below the barrier.

My guesstimate is that the G5 towers can handle 16 GB physically, but I have no way to verify that. Apart from that, I think it's just an academic question up till now.
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kogase
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Sep 13, 2004, 09:46 PM
 
I don't think 48-bit addressing handles 32TB of physical memory, but rather 32TB of virtual memory. I'm under the impression that a 64-bit addressing system supports up to 8GB of RAM.
     
OreoCookie
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Sep 14, 2004, 05:48 AM
 
I don't know about this, but with Panther, as mentioned before, it's not very useful to have that much RAM anyway. How can you check with Tiger?
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MrForgetable
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Sep 18, 2004, 01:21 AM
 
when will you ever use 8 100% processor intensive programs at one given time? must be one hell of a multi tasker.
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mjankor
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Sep 18, 2004, 03:31 AM
 
Actually a 64bit addressing system can support several exobytes of ram but the Northbridge chip on the G5's is only (I think) 42 bit.
     
andreas_g4
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Sep 18, 2004, 10:55 AM
 
16 GB of RAM cost an arm and a leg.
     
oeyvind
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Nov 30, 2004, 12:02 PM
 
16GB of RAM is possible via 2GB sticks according to the hardware dev notes.
     
Eug Wanker
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Nov 30, 2004, 03:21 PM
 
Originally posted by discstickers:
In 10.3, no app can use more than 2GB.
4 GB.

Also, you can run multiple apps simultaneously that can access that much memory.

Originally posted by oeyvind:
16GB of RAM is possible via 2GB sticks according to the hardware dev notes.
Correct. Apple itself says 16 GB will work.
     
Madrag
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Dec 4, 2004, 09:45 AM
 
Anyone care to try?


Now seriously, that'll be a great experiment, but I doubt 16GB are needed at this point...
     
   
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