iMac G5 with 4.5GB of RAM

[Project Alice]

Hey PPC forum

I picked up a 20" 2.1GHz iSight iMac G5 from shopgoodwill.com. It's in excellent shape, and I only paid $60 including shipping.
It's my first working iMac G5 (I have a 17" ALS model that doesn't turn on). I plugged it in and booted straight into an already clean install of Leopard 10.5.8. It had 1.5GB of RAM installed.

So this iMac apparently has a bit in common with the late 2005 PowerMacs; PCIe based graphics, and DDR2 memory. Since it only had 1.5GB I immediately wanted to upgrade to the "max" of 2.5GB. I grabbed one of my RAM bags, and sifting through it I found multiple 4GB DDR2 sticks. Since the G5 architecture is obviously able to address over 2GB unlike G4s, I decided to put it in and see what happens.
Before doing this I googled and found mostly nothing, but one page on Apple discussions about somebody asking if it was possible. It was filled with the usual "no it is not even remotely possible" type of replies; however the OP said he did it anyways and it worked, but no photo evidence was provided.

It worked, mostly. The only weird thing is that System Profiler shows "Empty" under the memory section. Other than that, the stick is recognized just fine. It is also very noticeably faster.


I'm wondering if the reason the memory tab says it is empty is because of the speed. I couldn't find a DDR2 stick slower than 666MHz. But as you can see, it works.

 

[TheShortTimer]

Congrats on your new addition and confirming the actual max RAM capacity.

It's extremely useful information for the community because as you know, the page on EveryMac lists 2.5GB as the absolute limit. We really ought to have a sticky for info like this because it would help to prolong the usage of older hardware and widen the scope of their capabilities. Imagine how many people own this model and are unawares that you can almost double the RAM size?

 

[retta283]

It seems very weird to me that this thing can address more RAM than its Intel successors up until the 2007-08 era. I wonder if it'd run unstable after a while using it with this upgrade, I recall that being a problem on some of these. I don't doubt that it works but it's baffling to see.

 

[Project Alice]

It seems very weird to me that this thing can address more RAM than its Intel successors up until the 2007-08 era. I wonder if it'd run unstable after a while using it with this upgrade, I recall that being a problem on some of these. I don't doubt that it works but it's baffling to see.

That limitation is because of Intel chipsets. All the PCs that used the Intel 800\900 series chipsets were plagued by the same limitations.
Remember the G5 is still a 64Bit architecture, even in the iMac. Core Duos are not. So even if the Intel chipset supported X amount of memory, it would only be able to address under 4GB. I'm not sure how familiar a lot of you are with PCs, but among the PC world those Intel chipsets used in the early Intel macs were considered entry level crap. The only one that wasn't was the Mac Pro, which was a modified Intel server board. I bet that's part of the reason the 2009 and 2010 Macs used a nvidia chipset instead.
I used to have a Dell laptop that was identical to a 2007 MacBook in every way. I was even able to run vanilla Snow Leopard on it with pretty much just the boot loader.

I've had it running all day and it's been fine. If anything weird happens I'll update the thread. I don't suspect it will though. Eventually I'll put an SSD in it, and I'll need to replace the optical drive because it won't read DVDs for some reason. It already feels just as fast as my dual 1.8Ghz.

 

[TheShortTimer]

Remember the G5 is still a 64Bit architecture, even in the iMac. Core Duos are not. So even if the Intel chipset supported X amount of memory, it would only be able to address under 4GB. I'm not sure how familiar a lot of you are with PCs, but among the PC world those Intel chipsets used in the early Intel macs were considered entry level crap. The only one that wasn't was the Mac Pro, which was a modified Intel server board. I bet that's part of the reason the 2009 and 2010 Macs used a nvidia chipset instead.

As I've droned on in the past, I witnessed scenarios where my PM G5 and my Core Duo Mac tackled the same task and the former wiped the floor with the latter, so this doesn't surprise me and if anything, it sheds a great deal of light on those experiences.

I used to have a Dell laptop that was identical to a 2007 MacBook in every way. I was even able to run vanilla Snow Leopard on it with pretty much just the boot loader.

Similarly I had a Dell Vostro 1510 that was able to run Leopard because the hardware was a very close match for the equivalent Apple laptop but eventually the amount of problems forced me to reinstall Windows.

 

[Amethyst1]

As I've droned on in the past, I witnessed scenarios where my PM G5 and my Core Duo Mac tackled the same task and the former wiped the floor with the latter,

Given that all Core Duo Macs were laptops (including the iMac!) and were also possibly held back by non-native applications, this is not surprising.

 

[Project Alice]

I just opened a bunch of apps, and a bunch of tabs in LWK and TFF to make sure it would actually continue working after 2.5GB

It does.

 

[TheShortTimer]

Given that all Core Duo Macs were laptops (including the iMac!) and were also possibly held back by non-native applications, this is not surprising.

The Core Duo iMac was a repackaged laptop?

Can you elaborate about this please?

 

[Project Alice]

The Core Duo iMac was a repackaged laptop?

Can you elaborate about this please?

It just uses mobile hardware. The MacMini does too.

 

[Amethyst1]

It just uses mobile hardware.

Yep. Mobile CPU, chipset and - iirc - GPU. The iMac's only benefits were a faster 3.5" HD and, for the white 20", a better (IPS) screen.

 

[Amethyst1]

just opened a bunch of apps, and a bunch of tabs in LWK and TFF to make sure it would actually continue working after 2.5GB

Now fire up some VPCs with 512MB assigned to each to totally fill the RAM

 

[retta283]

Yes, the Intel iMacs of the 2006-2009 era are pretty much just laptops with a big screen and internal power supply. It was only in late 2009 that the iMacs started to get more desktop parts in them, with desktop-class CPUs, some being Quad core. GPUs were still mostly mobility or integrated however, and RAM remained laptop-style. 2012 saw the loss of the 7200rpm 3.5" drives, one of the few consistent desktop staples in the iMac, replaced with a cheap 2.5" 5400rpm piece of junk. I remember the rage at Apple against that one in particular on these boards. 2012 was quite a bad year for Apple (at least in the eyes of this site it was), as a lot of people seem to forget now...

 

[Amethyst1]

2012 saw the loss of the 7200rpm 3.5" drives, one of the few consistent desktop staples in the iMac, replaced with a cheap 2.5" 5400rpm piece of junk.

And in 2014, the entry-level iMac was downgraded to a low-power dual-core CPU lifted straight from a MacBook Air. That in combination with the slow-as-heck HD was quite a deal at 1099 bucks. Or not. Oh well, at least it wasn't Core M'd in 2015

 

[dextructor]

I've got the same iMac iSight 20'' by 2020 christimas and I have some DDR2 (http://web-old.archive.org/web/20160308150939/http://ramlist.i4memory.com/ddr2/) modules from past PC builds that I tried with success over this last weeks. Both work besides the labeled speed and voltage differs from the manual and requirements that are avaliable over the internet. Obviously that the heatspreaders needed to be removed to be able to fit inside the machine, the speed in the "System Profiler" I guess that are reported wrong, but since I don't have any "regular non overclocking" DDR2 modules and no knowledge about some benchmark software like AIDA64 to specifically test the speed of the modules (on OSX or Linux) I would ask if you have any suggestion to help put some answers and numbers. I personally use the 996564 because I like more the Micron D9 + Brainpower PCB for performance on PC builds.

 

[Amethyst1]

But the real question is - does it also run stable on Tiger?

 

[Strategia]

2012 saw the loss of the 7200rpm 3.5" drives, one of the few consistent desktop staples in the iMac, replaced with a cheap 2.5" 5400rpm piece of junk.

Such a bad move from Apple. Until Mojave the 5400rpm drive was tolerable, but once Apple rolled out APFS for all drives it was much slower. It's a shame that many users won't go to the trouble of replacing it with an SSD - my 2013 iMac with an 860 EVO installed internally is still perfect on the "unsupported" Big Sur.

 

[Amethyst1]

Until Mojave the 5400rpm drive was tolerable,

I'll have to disagree. I have a 2015 iMac 4K with the 24GB PCIe SSD plus 1TB 2.5" 5400rpm HD "Fusion Drive" config - just for kicks I broke that up and ran El Capitan from the HD alone - it was just plain unbearable. I dread to think what later versions would be like. Heck, even the Fusion Drive drove me mad because performance plummeted when it had to access the HD - and with an SSD this small, this happened way more frequently than I liked. I bought an external SSD and couldn't be happier.

It's a shame that many users won't go to the trouble of replacing it with an SSD

Since you can just boot from an external SSD attached via FireWire 800, Thunderbolt or USB 3.0 depending on what iMac it is, it isn't much trouble at all actually.

 

[Strategia]

Since you can just boot from an external SSD attached via FireWire 800, Thunderbolt or USB 3.0 depending on what iMac it is, it isn't much trouble at all actually.

I suppose so. I used an external SSD within a USB enclosure before, and found it inconvenient that your entire OS could stop working as soon as you disconnected the cable.

 

[Amethyst1]

and found it inconvenient that your entire OS could stop working as soon as you disconnected the cable.

Why would I ever disconnect my external boot drive though?

 

[dextructor]

But the real question is - does it also run stable on Tiger?

With both sticks that I have tested... Yes it runs on Tiger very stable then I installed Leopard and Void Linux (everything works including the iSight cammera with the required firmware). Soon I plan to triple boot with MorphOS

 

[Amethyst1]

With both sticks that I have tested... Yes it runs on Tiger very stable then I installed Leopard and Void Linux. Soon I plan to triple boot with MorphOS

We're talking about 4.5 GB as tested by the OP, right?

 

[Project Alice]

But the real question is - does it also run stable on Tiger?

I shrunk the Leopard partition and installed Tiger on mine shortly after posting this thread. It works in Tiger too.

 

[RogerWilco6502]

Now fire up some VPCs with 512MB assigned to each to totally fill the RAM

I did that with my main system (a ThinkPad 32GB of RAM and 10 Windows 7 virtual machines with 2GB each IIRC) once.

 

[Project Alice]

But the real question is - does it also run stable on Tiger?

I shrunk the Leopard partition and installed Tiger on mine shortly after posting this thread. It works in Tiger too.

Thanks for that!

My iMac G5 successfully finished compiling the 7450 version. I’m just about to leave for work this morning but I did launch it and it seemed to be working good.

Just thought I'd give a quick update here. Those following the InterWebPPC thread; I just used my iMac G5 with 4.5GB RAM to compile a 7450 version of IWPPC. I did this running under Tiger as recommended. I started it at like 8PM and then went to bed. When I woke up at 4am for work, it was all finished and the browser was working.

 

[netsrot39]

Wow, this is an amazing finding. I also have a Late 2005 iMac G5 with 2.5 GB of memory installed but I'd of course not say no to having 2 GB more. Just to be clear, one can use PC2 6400 800 Mhz sticks, correct? I've found many sticks intended for the AMD platform online for very cheap and I'm wondering if those could possibly work. I'm really tempted to buy one or two sticks to try it out since a single stick can be already had for about 8€ and the only answer to an affordable and useful upgrade can be yes . Can you recommend a certain chip brand? Also could the voltage difference be of concern? Thanks!