iMac G5 with 4.5GB of RAM

[tigerintank]

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.

Will this work with an iMac G5 that's pre iSight? I have a 2.0GHz G5 that as far a I now is 2G RAM max.

 

[dextructor]

Will this work with an iMac G5 that's pre iSight? I have a 2.0GHz G5 that as far a I now is 2G RAM max.

Probably not, because if your model it's the PowerMac8,2 - A1076 and if the webpage it's accurate you have DDR memory instead of DDR2 memory. So far to my knowledge DDR don't have 2GB sticks without being ECC. So if you wanna try for the sake of science like some of our folks did and find that your iMac accept DDR 400 ECC with 2GB per stick, we welcome you.

 

[tigerintank]

Probably not, because if your model it's the PowerMac8,2 - A1076 and if the webpage it's accurate you have DDR memory instead of DDR2 memory. So far to my knowledge DDR don't have 2GB sticks without being ECC. So if you wanna try for the sake of science like some of our folks did and find that your iMac accept DDR 400 ECC with 2GB per stick, we welcome you.

Yes its that one.

Well having looked at that page it feels like a slim chance. Having said that I'd be happy to try it if someone wanted to post me a stick or 2 - I'd return it of course. Wouldn't buy any though as I don't have any need elsewhere if it didn't work.

 

[Project Alice]

Yes its that one.

Well having looked at that page it feels like a slim chance. Having said that I'd be happy to try it if someone wanted to post me a stick or 2 - I'd return it of course. Wouldn't buy any though as I don't have any need elsewhere if it didn't work.

I don't have any 2GB DDR sticks but yes it appears it's only available in ECC. The PowerMac G5 supports ECC memory as long as it's unbuffered\Unregistered. It is possible the same applies for the iMac.

 

[netsrot39]

Tonight I've tried upgrading my iMac G5 iSight to 4.5 GB of RAM and it worked!!! I can confirm @Project Alice findings. It indeed does seem to utilize all the memory available and is stable (I've only tested 1 hour so far). The only weird thing is, like @Project Alice has already pointed out, that the 4GB RAM stick actually shows up as empty in System Profiler. Right now I can't really tell the difference, the machine is quite snappy, but to be honest it was pretty snappy before. I will have to benchmark some stuff to note the difference between 2.5 GB and 4.5 GB of RAM, it is not evident right away. For browsing the web, that I can tell, I don't really see a lot of improvement (probably mostly CPU dependent).

I would say in conclusion the upgrade was worth it, I now have 2 GB of additional memory for the mere cost of 7€. I will just have to find some use cases where they come in handy. In case anybody is interested, this is the RAM module I'm using: https://www.amazon.de/gp/aw/d/B08CDCGYP5?psc=1&ref=ppx_pop_mob_b_asin_title#

 

[dextructor]

One more to confirm the results of other members with 4GB sticks on the iMac G5 2.1 20" iSight. Yesterday arrived my Mushkin Silverline 991763 modules to test, and today I must say thank you @Project Alice for your discoveries, so far working great but the heatsink must gone to properly enter (just like my other 2GB stick)

 

[sbarton]

so who's going to try the 8gb DIMM?

 

[netsrot39]

so who's going to try the 8gb DIMM?

I probably would if I could find an 8gb memory stick. So far I have only been able to find an 8GB DDR2 server grade memory stick but I'm not really sure if the iMac G5 can utilize ECC memory. There are rumours that the Late 2005 PowerMac G5 can utilize server memory but afaik all memory has to be the same type. Now I could imagine the same applies to the Late 2005 iMac G5 (since it also uses DDR2) but then again we would have the problem of the internal memory not being ECC (not really sure though if that matters and if my thoughts on this are correct but that is what I'd assume).

 

[sbarton]

The G5's can if the memory is unregistered, and thats pretty rare with ECC ram.

 

[lepidotós]

It's extremely useful information for the community because as you know, the page on EveryMac lists 2.5GB as the absolute limit.

I keep forgetting they're not an accurate source of information, then something like this comes along and sets me straight.​

 

[everymac]

I keep forgetting they're not an accurate source of information, then something like this comes along and sets me straight.​

It is not uncommon for Maximum RAM to change over time as higher capacity memory modules are introduced. If you install more RAM in a Mac or Mac clone than is officially supported by the manufacturer and it runs stably without errors for a significant length of time, please get in touch via email so that information can be updated or expanded as needed. Thank you.

 

[pc297]

Tonight I've tried upgrading my iMac G5 iSight to 4.5 GB of RAM and it worked!!! I can confirm @Project Alice findings. It indeed does seem to utilize all the memory available and is stable (I've only tested 1 hour so far). The only weird thing is, like @Project Alice has already pointed out, that the 4GB RAM stick actually shows up as empty in System Profiler. Right now I can't really tell the difference, the machine is quite snappy, but to be honest it was pretty snappy before. I will have to benchmark some stuff to note the difference between 2.5 GB and 4.5 GB of RAM, it is not evident right away. For browsing the web, that I can tell, I don't really see a lot of improvement (probably mostly CPU dependent).

I would say in conclusion the upgrade was worth it, I now have 2 GB of additional memory for the mere cost of 7€. I will just have to find some use cases where they come in handy. In case anybody is interested, this is the RAM module I'm using: https://www.amazon.de/gp/aw/d/B08CDCGYP5?psc=1&ref=ppx_pop_mob_b_asin_title#

One more to confirm the results of other members with 4GB sticks on the iMac G5 2.1 20" iSight. Yesterday arrived my Mushkin Silverline 991763 modules to test, and today I must say thank you @Project Alice for your discoveries, so far working great but the heatsink must gone to properly enter (just like my other 2GB stick)

Any idea whether those will work on the dual-core or quad G5?

 

[Project Alice]

Any idea whether those will work on the dual-core or quad G5?

There have been rumors the G5 quad will take 32GB. But I can't test it as I only possess a broken G5 Quad. All my other G5s are earlier 2003 and 2004 models that are DDR1.

I wouldn't be surprised if it works though.

 

[Amethyst1]

There have been rumors the G5 quad will take 32GB.

#171

 

[pc297]

There have been rumors the G5 quad will take 32GB. But I can't test it as I only possess a broken G5 Quad. All my other G5s are earlier 2003 and 2004 models that are DDR1.

I wouldn't be surprised if it works though.

32Gb is most probably supported, the real deal is to find affordable 4Gb modules. Allegedly the Komputerbay 4Gb UDIMM modules work but you're talking about $130 a pair (brand new) or maybe $50-$60 second hand, quite an investment for 32Gb.

I did have a go at the 800MHz of a clone of the Yunir 4Gb AMD-only sticks mentioned above on the Quad https://www.amazon.de/gp/product/B086K5GMQ2/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

Identical to the Yunir RAM in every aspect except the ASIN.

However I am greeted with 3 beeps after the chime (using a pair of that RAM only), and if I add it to existing UDIMMs, the AMD-only sticks are not detected. So a rather solid no on that front, at least for 800MHz.

I might give it a try with 667MHz sticks.

Cheers,


EDIT: This now works on the G5 Quad with the OpenFirmware from @sasho648, see

https://forums.macrumors.com/threads/g5-quad-32gb-possible.1126338/post-31730903

 

[pc297]

I probably would if I could find an 8gb memory stick. So far I have only been able to find an 8GB DDR2 server grade memory stick but I'm not really sure if the iMac G5 can utilize ECC memory. There are rumours that the Late 2005 PowerMac G5 can utilize server memory but afaik all memory has to be the same type. Now I could imagine the same applies to the Late 2005 iMac G5 (since it also uses DDR2) but then again we would have the problem of the internal memory not being ECC (not really sure though if that matters and if my thoughts on this are correct but that is what I'd assume).

Most, if not all 8Gb DDR2 DIMMs are ECC AND registered, and registered memory doesn't work in the G5. I tried a 4Gb Reg ECC pair and it's a no-go. However, non-registered ECC is supported and can be mixed with non-ECC memory on the G5, I currently have such a setup, with 4x2Gb ECC and 4x1Gb non-ECC, just make sure that you use the ECC sticks in pairs and don't mix ECC and non-ECC in the same pair. I have however yet to see a 4Gb let alone 8Gb non-registered ECC DDR2 stick.

 

[pc297]

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.

View attachment 1719558
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.
View attachment 1719559

View attachment 1719560

Hey Alice,

If you want the stick to show up in ASP I guess you need to manually add the ram size in OF as for the G5 Quad, e.g.

dev /memory
" "(20000000FFFFFFFF)" encode-bytes " bank-sizes" property

Cheers,

 

[dextructor]

If you want the stick to show up in ASP I guess you need to manually add the ram size in OF as for the G5 Quad, e.g.

dev /memory
" "(20000000FFFFFFFF)" encode-bytes " bank-sizes" property

Hi

I tested several times, but all failed. I even reset the NVRAM to avoid some potential error scenarios.

First I entered the code and since my machine boot automatically to Void Linux I used "multi-boot" to select the OSX partition, but no luck.

Then I reset the NVRAM and tested again, but my iMac don't locate automatically the OSX partition when I type "mac-boot".

So I tried to boot directly the same way that you did on the G5 quad "boot sd0:8,\\:tbxi" but even the error in System Profiler appeared "There was an error while gathering this information"

So at least for now on my iMac G5 iSight with the OpenFirmware 5.2.6f1 this code don't work to show correctly the memory on System Profiler, but in my Void Linux trying to get the memory size I didn't get any errors(but I don't remember the command that I used)

Thanks for the suggestions

 

[pc297]

Hi

I tested several times, but all failed. I even reset the NVRAM to avoid some potential error scenarios.

First I entered the code and since my machine boot automatically to Void Linux I used "multi-boot" to select the OSX partition, but no luck.

Then I reset the NVRAM and tested again, but my iMac don't locate automatically the OSX partition when I type "mac-boot".

So I tried to boot directly the same way that you did on the G5 quad "boot sd0:8,\\:tbxi" but even the error in System Profiler appeared "There was an error while gathering this information"

So at least for now on my iMac G5 iSight with the OpenFirmware 5.2.6f1 this code don't work to show correctly the memory on System Profiler, but in my Void Linux trying to get the memory size I didn't get any errors(but I don't remember the command that I used)

Thanks for the suggestions

Sorry that it didn't work, could you post the output of

dev /memory
.properties

in OpenFirmware after reset? (the bank-sizes command is volatile)

 

[dextructor]

Sorry that it didn't work, could you post the output of in OpenFirmware after reset? (the bank-sizes command is volatile)

No need to be sorry, like I said, if it's only cosmetic I don't have any trouble, but I'm here to help others as well. Since I don't know exactly what piece of information, here's the output of the command

name            memory
device_type        memory
reg            00000000  00000000  20000000
            00000000  00000000  00000000
            00000000  00000000  00000000
            00000000  00000000  00000000
            00000000  20000000  60000000
            00000001  00000000  a0000000
            00000000  00000000  00000000
            00000000  00000000  00000000
            00000003
slot-names        DIMM0/BUILT-IN
            DIMM1/J6700
available        pseudo=00003000  7f9ed000
ram-map            00000001  80000000  20000000  00000000 00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000 00000000  80000000  00000001  00000000  800000000 00000000  00000000  00000000  00000000  00000000  00000000
            0000000f
            32 bit Bank0/BUILT-IN/front
            32 bit Bank4/J6700/front
            32 bit Bank5/J6700/back
bank-sizes        20000000  00000000  80000000  80000000
            8000000e  0a040000  003d0000  00000000  00000400  02000000 0000003c  003c2800  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000
            00000000  00000000  00000000  00000000  8008080f  0a614000  05254000 82080000  0c087001  02000730  453d503c  1e3c2d02  17250512  3c1e1e00  003cc380  141e0000  00000000  00000000  00000000  00001221  7f7f7f94  ffffffff  01393931  37363320  28393936  37363329  00000000  00000000
            00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000
dimm-types        DDR2 SDRAM
            DDR2 SDRAM
dimm-speeds        PC2-4200U-444
            PC2-3200U-288
ram-layout-architecture 00000002
ram-bus-width        00000080

I hope that helps

 

[pc297]

No need to be sorry, like I said, if it's only cosmetic I don't have any trouble, but I'm here to help others as well. Since I don't know exactly what piece of information, here's the output of the command

name            memory
device_type        memory
reg            00000000  00000000  20000000
            00000000  00000000  00000000
            00000000  00000000  00000000
            00000000  00000000  00000000
            00000000  20000000  60000000
            00000001  00000000  a0000000
            00000000  00000000  00000000
            00000000  00000000  00000000
            00000003
slot-names        DIMM0/BUILT-IN
            DIMM1/J6700
available        pseudo=00003000  7f9ed000
ram-map            00000001  80000000  20000000  00000000 00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000 00000000  80000000  00000001  00000000  800000000 00000000  00000000  00000000  00000000  00000000  00000000
            0000000f
            32 bit Bank0/BUILT-IN/front
            32 bit Bank4/J6700/front
            32 bit Bank5/J6700/back
bank-sizes        20000000  00000000  80000000  80000000
            8000000e  0a040000  003d0000  00000000  00000400  02000000 0000003c  003c2800  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000
            00000000  00000000  00000000  00000000  8008080f  0a614000  05254000 82080000  0c087001  02000730  453d503c  1e3c2d02  17250512  3c1e1e00  003cc380  141e0000  00000000  00000000  00000000  00001221  7f7f7f94  ffffffff  01393931  37363320  28393936  37363329  00000000  00000000
            00000000  00000000  00000000  00000000  00000000  00000000  00000000  00000000
dimm-types        DDR2 SDRAM
            DDR2 SDRAM
dimm-speeds        PC2-4200U-444
            PC2-3200U-288
ram-layout-architecture 00000002
ram-bus-width        00000080

I hope that helps

Thanks! Is this after reset and before any of the "encode-bytes" OF commands? "reg" looks like it has one too many lines and incomplete and "ram-map" looks like it has one too many items (at least compared to the Quad). I see, the stick corresponds to two banks in the case of the iMac G5 iSight, "bank-sizes" looks like it already has the right sizes.

 

[dextructor]

Thanks! Is this after reset and before any of the "encode-bytes" OF commands? "reg" looks like it has one too many lines and incomplete and "ram-map" looks like it has one too many items (at least compared to the Quad). I see, the stick corresponds to two banks in the case of the iMac G5 iSight, "bank-sizes" looks like it already has the right sizes.

Well I did reset everything yesterday, but to be safe I did reset just now and compared, but no changes. I typed because having to look to the picture, zooming isn't a good idea when having to do some analysis with data. But here's the picture.

 

[pc297]

Well I did reset everything yesterday, but to be safe I did reset just now and compared, but no changes. I typed because having to look to the picture, zooming isn't a good idea when having to do some analysis with data. But here's the picture.

Thanks for the pic this helps along with the text, the totals do seem to add up (60000000+A0000000=100000000 which is 4Gb), what is weird is that the iMac doesn't split the DIMM in two even banks; what if we try to do it manually?
e.g.

" "(000000000000000020000000000000000000000000000000000000000000000000000000000000000000000000000000000000002000000080000000000000010000000080000000000000000000000000000000000000000000000000000000)" encode-bytes " reg" property

Or you could try to fit the whole DIMM on one bank and adjust "bank-sizes" accordingly:

" "(0000000000000000200000000000000000000000000000000000000000000000000000000000000000000000000000000000000020000000F0000000000000000000000000000000000000000000000000000000000000000000000000000000)" encode-bytes " reg" property
" "(2000000000000000FFFFFFFF00000000)" encode-bytes " bank-sizes" property

 

[dextructor]

Or you could try to fit the whole DIMM on one bank and adjust "bank-sizes" accordingly:

Well I combined your latest suggestion and it worked. Thanks!

dev /memory
" "(2000000000000000FFFFFFFF00000000)" encode-bytes " bank-sizes" property
boot sd0:8,\\:tbxi

I didn't test the longest first line so far, because it will take more time just to make sure won't have any mistakes.

So, the thing it's to find a way to implement it, taking into consideration that my primary Operating System it's Linux (Void) and there isn't any problem detecting the memory.

And I asked you a question some time last year about larger DDR2 sticks than 4Gb for our G5's, can you answer that please? 2Gb that it's the official max that this model support I can fill without much effort, 4Gb it takes much more effort, but 8Gb I can't think a way to use it even in normal circumstances in my X86 machines unless I'm using Virtual Machines or some other things that complex.

 

[pc297]

Well I combined your latest suggestion and it worked. Thanks!

dev /memory
" "(2000000000000000FFFFFFFF00000000)" encode-bytes " bank-sizes" property
boot sd0:8,\\:tbxi

I didn't test the longest first line so far, because it will take more time just to make sure won't have any mistakes.

Glad it worked, congrats! Did try to use all the memory from using the default "reg" setting, it's somehow awkward that the stick is split in two uneven banks, make sure it's all functional (e.g. make -j2 or -4, should do it on the iMac G5) and if it isn't I would try the first long command.

So, the thing it's to find a way to implement it, taking into consideration that my primary Operating System it's Linux (Void) and there isn't any problem detecting the memory.

How do you boot Void? If it's from an hfs bootstrap partition I had found a solution that entailed simply pasting in the OF command in ofboot.b before the boot command right at the end. For OSX, check out this very simple solution found by @sasho648 which involves creating a .ramsc file:

https://forums.macrumors.com/threads/g5-quad-32gb-possible.1126338/post-31702300

And I asked you a question some time last year about larger DDR2 sticks than 4Gb for our G5's, can you answer that please?

Apologies for not replying any sooner; so it's

2x 2G (to get to OF)

Kingston 2GB DDR2 533 (PC2 4200) Desktop Memory Model KVR533D2N4/2G - Newegg.com

Buy Kingston 2GB DDR2 533 (PC2 4200) Desktop Memory Model KVR533D2N4/2G with fast shipping and top-rated customer service. Once you know, you Newegg!

www.newegg.com

plus 2x 4G

Crucial CT51264AA667 4GB 240-pin DIMM DDR2 PC2-5300 Memory Module

Every day, you rely on your computer to make your life easier. A Crucial DRAM upgrade can help your system run faster, and it's one of the easiest, most affordable ways to improve system performance. Reap the benefits doing everything from everyday system tasks to mission-critical applications. F...

www.amazon.com

plus 4x 4G

4GB DDR2-4GB 800MHz DDR2 Memory Module High Capacity 800MHz Fast Data Transmission DDR2 RAM

4GB DDR2-4GB 800MHz DDR2 Memory Module High Capacity 800MHz Fast Data Transmission DDR2 RAM

www.amazon.com

But I guess 2x of the first one plus 6x of any of the last two above will do. The really great thing is that "AMD-only" high-density memory works fine in our G5s (the last 4 sticks). The first two 4G sticks are "Intel-compatible".

2Gb that it's the official max that this model support I can fill without much effort, 4Gb it takes much more effort, but 8Gb I can't think a way to use it even in normal circumstances in my X86 machines unless I'm using Virtual Machines or some other things that complex.

You'd be surprised how much vector graphics can eat up memory so for Illustrator or Inkscape it's great! Re 8Gb sticks we're not there yet, there's another OpenFirmware limitation in that the while the memory address location is encoded as 64-bit, the memory address range is encoded as 32-bit so we would need to find a way to change that to 64-bit, e.g. changing #size-cells to <2> from " reg" in /memory (instead of <1>), but I haven't yet figured out a way to do that if it's at all possible. And it also looks like registered or parity memory is mostly a no-go,which encompasses all 8Gb sticks, unless anyone has ever come across 8Gb DDR2 UDIMMs.

I am saying mostly because once or twice I did get to OF with them as a pair (plus regular 2Gb sticks of course) where they were detected properly as "PC2-4200-R" (it was with registered RAM), but it mostly ends up in the telephone beep, why this randomly seldom succeeds is so far beyond me. It could have been a very lucky combination which I haven't been able to recreate. Strangely enough on their own (e.g. mixing one PC2-4200-R or -P with a regular UDIMM) they are detected fine but the boot process crashes.

Cheers,