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G5 mod with intact case and reused PSU

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Hello, all. I was in the market for a used Intel based Mac, but when I saw this G5, I got a great idea. Little did I know that there is a whole community of people with the same idea. When my wife saw the computer, she immediately asked if she can have it, so I said sure. So, here I am, typing on her new shiny G5.

IMG_0318.jpg

I wanted to preserve as much as possible the original appearance, both inside and especially outside. I also wanted to minimize noise, which shouldn't be too difficult as this is a low power system with onboard graphics, that, like most of my computers, originated as an HTPC (home theater computer). So here it the build:

My test motherboard placed in the case; a different one goes into the final build, but I couldn't use it until everything else was in place and tested, and then I had only about an hour to do the switchover. Note the back panel cut from the original G5 logic board.

IMG_0281.jpg


Then I had to figure out the front panel pinout and do the harness; first the power switch and led, then usb and headphones:

IMG_0282.jpgIMG_0283.jpgIMG_0284.jpgIMG_0290.jpgIMG_0289.jpg


So far, so good. Next is figuring out the PSU pinout.

IMG_0293.jpg


Success; now make a replacement ATX power cable. This was tucked in more in the final build.

IMG_0298.jpg


Ready to Gorilla superglue (the miracle adhesive from my other hobby) the standoffs in ATX positions.

IMG_0299.jpg


Ah, the quiestion of position and orientation. The first is what I originally thought, but check out the IDE and SATA connectors in the other one. Quite compelling. I ultimately decided to go with the first one because the G5 fan assembly was interfering with the CPU fan.

IMG_0301.jpgIMG_0300.jpg


Now to the back panel. In addition to analog audio, usb, and ethernet, I did optical audio, but didn't bother with FireWire.

IMG_0310.jpg


For video output, I didn't feel like putting three feet of video cable in the case, and if I have to cut it and solder anyway, then I won't need to run to the store or order online. So I used a spare adapter and some leftover CAT5 cable. Color coding turned out to be most useful. This was probably the harderst part of the mod. It gave me some trouble dremmelling a back expansion cover, and then it wouldn't take solder at all. I had to superglue it, but I'm pleased with the outcome. For the time being, it's only a single HDMI, but in future builds I can revisit this.

IMG_0311.jpgIMG_0313.jpg


Ready to assemble everything. Oops, there goes my clean cable management. The SATA cabe is shorter than I thought, and will have to go above the board. Note how I striped the IDE cable for the optical drive, so it looks better, and more importantly, it reaches the drive. It looks a little bit better on the final board, as I have a little more space there. I replaced the superdrive with a blu-ray drive, so we can play movies on this, too.

IMG_0315.jpg


Fans and cover in place, and the back of the case; ready to go:

IMG_0316.jpgIMG_0317.jpg


Or I though so... Turns out the PSU fans are really noisy, so I first turned them off, thinking this is a low power system, and it's all attached to a lot of aluminum, so it won't overheat, but after a few hours, it was getting hotter, so I decided to put a silent 80 mm fan I had lying around, and now it's almost silent. The only problem is that can't use the PSU cover, but that's okay. I don't want to cut it, as I'm planning to use a picopsu (from mini-box.com) and a power brick instead. I have a similar setup in my HTPC, and it works great. Just like in that project, the powerbrick will be inside the case.

The finished computer in its environment:

IMG_0319.jpgIMG_0320.jpgIMG_0321.jpg


Thanks for following. Looking forward to any comments.
 
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Great Mod !

Few Qs though :p

Firstly, am I right in thinking that you've managed to use the original G5 PSU in its entirety ? I've never actually seen that done before and if you've got a few more pictures of how you did it I'd be very grateful!

Also, how did you clean the steel parts so well ?!? I've tried every metal cleaner in the kitchen cupboard but mine still looks 'smeared'. Yours looks flawless
 

eelhead

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What is the pin out that you used to wire up the G5 PSU to the ATX board.

I've seen several attempts and all fail due to power management issues because the logicboard utilizes power from a PSU differently then an ATX board. Aquamac forum has several of these threads all ending in non-completion in the conversion.

Also why use a PSU that is 6 to 9 years old? I also know they go from 450w in 2003 all the way to 1000w in late 2005
 
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Good work! :thumbup:

The reusing of the PSU is interesting, but I think not very energy efficient. Now you should replace Windows with OS X :cool:

MacTester
 
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If the G5 PSU overheats, but you can actually run your system from a PicoPSU, I'd say that is a pretty good indicator for not wasting time on re-using the Mac supply.....

Like Eel, I have seen a few threads indicating that the plan was to re-use the G5 supply and not seen any of them actually end very well. There was a thread on here earlier in the year that basically gave the pinout for the conversion for the supplies and which looked promising - but again I noted that there was never a final post saying that the result was a success.

I almost dived into one of these conversions myself as as I have one of the late 2005 supplies with 1000w but I decided against it as these have a remarkably complicated configuration (with metal tabs in place of ATX plugs) and surprisingly little written about their pinouts on the web. The second factor that put me off was that I read a statistic about how many G5s fail because of premature PSU death. Generally the PSU was always a weak link and so re-using a 7 to 10 year old supply with a reputation for unreliability even when new seems to be not the greatest move.
 

neilhart

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DJ79 - Welcome to the forum and thank you for posting your G5 PM hack. I am impressed with your PSU re-use as I never quite resolved the ATX power good signal when I tried to re-use a Mac Pro PSU. If you would document the conversion that would be great and should go into the G5 resource thread found at the top,

Keep on with the good work.
neil
 
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Very Really Nice Mod on G5. Looks so clear and clean. :thumbup:

Would you mind sharing the way you did wired old PSU with motherboard?. It should be better if you can show your wire diagram.

Thanks.
Noom.
 
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About the PSU:
I did it just out of curiosity. Based on what I saw on the forums, I set my expectations low. I knew that architecturally it isn't very different from an ATX one with most demand from the 12V lines, but I wasn't sure about any implementation differences. I planned from the beginning to use a PicoPSU, but I had to order it online (I have received it in the meantime; still need to find a good inexpensive 120W power brick).
The PSUs I had lying around were probably as old as the one from the G5, so I didn't want to bother with them, and I thought that with 600W available, even at 60% efficiency at 40-100W typical loads, it's going to be ok, so why not try it. If it doesn't work, it's going to delay me several days until the parts arrive, and if it does, then I wouldn't need to do any modifications to the wiring for the hard drives, nor mounting the powerbrick and rerouting AC leads, and that kind of stuff. I can do those things later incrementally.

I didn't make any internal pictures of the PSU, but you can zoom in the picture of the working computer with the PSU outside the case. I can take a picture later when I replace it with a PicoPSU if there's interest.
Basically, I had to split the ATX wires to P1 and P2 connectors. The extension cable that I used for testing was so confusing with different colors, so I had to check the connections several time before I finally swithced it on. For this test I took the 4-pin CPU cable from the P3 connector, which reduced guesswork, but I used it from P2 in the final build.
After the test, I cut off the ATX cable from an old PSU, and connected it directly to the P1 and P2 connectors. I soldered the ends of wires to correct thickness, and I plugged them into P1 and P2 connectors. It's quite secure. I'm not sure how difficult it would be to draw the diagram, but if used G5 and ATX diagrams found on this forum and other places on the net, and I consulted the official ATX specification document (I can't search for it now, but it should be easy to find).
In a nutshell, the color coding is almost identical: black is GND, yellow in 12V, red is 5V, orange is 3.3V, PWR_ON signal is green, -12V is blue, not sure if I'm forgetting anything. -5V on ATX can be ignored. The only thing that I wasn't sure about was the Power OK signal. ATX documentation says the PSU sends 5V on it once the voltages have stabilized (which is often implemented by a simple timer, and not by any measurements) and, in theory, turns it off in case of a brown out. The motherboard then keeps the CPU in reset state while this signal is inactive. They recommend (to PSU builders, I guess) not just connecting the regular 5V signal, because it would have to drop to about 2.4V or so before the motherboard would interpret it as inactive.
The G5, apparently, doesn't do this, at least to my knowledge, so I thought the risk would be low if I do exactly that (connect a red 5V line to this pin), and that's exactly what I did, and probably what many cheap PSUs do anyway.
Another item that needed attention was the 12V line. There is a single 12V pin on the ATX 20 connector (and two more on the 24 pin), which comes from P1. The 4-pin CPU cable gets it from a separate 12V source. On the P2, it's the yellow lines closest to the 25V line. So, in summary:
P1: GND, -12V, PWR_ON, (anything else?) to corresponding pins on ATX20 (and perhaps GND to ATX4)
P2: 5V, 3.3V, 12V_v2 to corresponding pins on ATX20; 12V_v3 to ATX4; also 5V to PWR_OK on ATX20
P3: direct to optical and hard drives

Nick, I thought the steel parts showed some finger marks, too, but, overall, I was amazed how clean and dust-free the whole computer was.

And, MacTester, since this is my wife's computer, it had to be Windows. But she loves the galaxy background.
 

JBG

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Very nice build dude ...

I look forward to use the backside too like you did, great work, spend a lot of time too :)
And look to my build if you wanna place the CPU cover back, just modify the middle shield (so it will fit over the motherboard)
and put back the power-supply-cover then you have also a great place to hang in the front fan's too.
 
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Nice work, really like the idea of keeping the back as original as possible.

When you say you did "optical audio". How do you do?
What are the pinouts on the apple optical audio modules, and where do you connect the pins on your motherboard? Does the motherboard need something special to be able to re-wire the optical ports?

BR
Anders
 
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