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iMac G4 20-inch Skull Canyon NUC

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Hi everyone.

This will be my first hackintosh build, and will replace my current Mac Pro. I need a machine that's easier to move around, but still packs some power. My first thought was to get a new iMac. But first and foremost, I am not a big fan of the “new” aluminium design. Furthermore, they are quite pricey, especially if you want a discrete GPU. But the NUC doesn’t have a discrete GPU either, you might say. I will come back to that.

I used to have a 15-inch iMac G4, and I have always drooled at the 20-inch model. After some googling, I was amazed by a lot of the hacks that people have done to it. Since I do a lot of writing and research, and need to be able to comfortably view two documents at a time, I believe 20-inch is the lowest I can go.

But as it seems, these are not easy to get a hold of. At least not in the time of writing this. I came over a mint condition 20-inch base with neck last week, and quite impulsively put a bid on it, which I ended up winning. I kind of regret this, since a flawless display assembly seems hard to obtain. At least for an amount of money that is not insane. And just recently a complete machine showed up on eBay…. I should have waited. Nonetheless, since I have already bought the base, the hunt for a screen assembly continues (there’s one on eBay right now, but he will not ship it to me).

Meanwhile, I’ll try to do some planning.

As the title points out, I’m thinking about putting a NUC Skull Canyon nuc6i7kyk in it. It has an i7-6770HQ processor, and Iris Pro Graphics 580. It’s an all right performing CPU, coupled with what seems to be an adequate GPU (considering it’s an integrated one). More importantly, it has a Thunderbolt 3 port. This will let me connect devices like the Razer Core External Graphics Dock, and let me put in my GTX 960 when needed. This will probably not work under Mac OS X, but that’s okay. I am just a casual gamer, and I do not require it to be plugged in all the time. It also seems like the new NUC is quite hackintoshable, except for the new Wi-Fi and Bluetooth chip that is soldered on. I guess I’ll just be using a USB dongle then, or Ethernet.

The size of the new NUC is a bit different than the old one though, with it being 21,1 cm x 11,6 cm. According to my very unscientific sketches, it should fit.

imac g4 nuc.jpg

I’m planning to use the internal PSU to power both the NUC and the screen. I think that’s the most elegant solution, plus I get to reuse a perfectly fine PSU. I will remove the DVD-drive, mostly to achieve better cooling and make the job easier.

That’s it for now. I have ordered some generic parts on eBay, like the DVI molex thingy that Dremel Junkie recommends, some upconverters and downconverters etc.

I am really excited to do this mod, and will keep you guys updated on how it goes. As I have already pointed out, I have never done this kind of a mod before, though I do know my way around computers. I guess the hardest part will be the PSU, as I have no experience in that area…

Every tip will be greatly appreciated. And if any of you have a 20-inch LCD laying around, I’d be happy to buy it off you.
 
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Looking forward to seeing the progress and outcome of this. I'm eyeballing the skull canyon myself for a future build.
 
A quick update on the project. I am going away for some days, so thought I would write a short summary of the work so far.

I received the base, and got hold of a display assembly. The screen is actually from an iMac G5. Everything works perfectly. Still waiting for the bezel though.

IMG_0481.JPG

Test-fitting the NUC:
IMG_0495.JPG IMG_0499.JPG

With some cable extenders. They are a bit long, but that's all I have for now.
IMG_0604.JPG

I decided to use the dremel on the motherboard, and remove everything except for the back part. I will glue the ports to this, and rewire the original power button to the NUC.
IMG_0619.JPG IMG_0622.JPG

Wiring the TMDS cables...
IMG_0625.JPG IMG_0633.JPGIMG_0634.JPG

A 12v to 19v adapter to power the NUC. Bolted to the DVD casing.
IMG_0629.JPG

The fan is wired to a USB cable, which is powered by a USB port on the NUC. This means no fan control, but the 5v from the USB port provides a pleasant RPM. Hopefully it will push enough air to keep the NUC cool.

There is one problem though. The screen works perfectly when connected. There's no artifacts or noise. But when I disconnect the HDMI-cable from the DVI - HDMI adapter (or the machine goes to sleep), the screen goes into a "colour loop". Really strange. It goes grey, white, black, red, green, blue, and a bunch of different colours... It changes about every three seconds.

I have checked all the cables, and even rewired it again. Do any of you have an idea of what might be wrong?
 

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If your display panel is from an isight 20" G5 then I have one that does the exact same behaviour when it goes to sleep.
 
Good to know I'm not the only one. Did you ever get it sorted?

Maybe I should fix it with a power switch on the 24v or 5v white and blue cable to the PSU?
 
Good to know I'm not the only one. Did you ever get it sorted?

Maybe I should fix it with a power switch on the 24v or 5v white and blue cable to the PSU?

As far as I know, unless there's some way you can shut off the inverter when sleep is detected, the color cycling will be something that you'll have to put up with. I have a previous gen iMac (A1076) that doesn't display the same behaviour. It simply goes black when sleep is initiated.

My iSight 20" mod works perfectly, other than the rotating colors prior to sleep. For the few seconds it takes, I'm not going to bother with trying to remedy it.

Cheers!
 
So the rotating colours on your display goes away after a few seconds? I left mine on yesterday just to test for half an hour, but the screen was still fully lit with the rotating colours.

I think I will try to put a power switch on the the white wire, and see how it works. It's not optimal, since I will have to install another physical button on the outside of the machine, but worth a try.
 
Major update today :)

First I fitted all the cables as low as I could. Had to put the dremel to the metal on the DVD-case. The NUC wouldn't fit when trying to close it all together, so I had to shave it. I also moved the 19v transformator for better cooling for the NUC. Since the NUC only has 4 USB ports, and one goes to the USB sound card and one to the fan, only two of the back ports are actually connected. This will be fixed in the future.
FullSizeRender.jpg IMG_0723.JPG

The NUCs new home. Tight fit.
IMG_0729.JPG

Then I installed a power switch on the white 5v wire. This works great, and turns the screen on and off as desired. If I could I would drop it, but when my NUC goes into sleep the screen starts an endless colour loop. Now the screen can stay off when the computer sleeps.
IMG_0725.JPG

I have also wired the original power button on the G4 logic board to the NUCs Internal Common IO header. Number 14 and 15 are the pins I used. I reused some cables from an additional neck to connect to it, just like the DVI-mod. The port is easily accessible from the bottom.

Screen Shot 2016-07-15 at 17.25.13.png IMG_0726.JPG

All closed up and ready for some testing! The temperature was stable and cool. It seems like the USB-powered fan provides adequate cooling (yes, I tested it after mounting the front plate of the DVD drive to, still cool :cool:).
IMG_0732.JPG IMG_0733.JPG

The back ports look like this:
imac g700.jpg imac g701.jpg

From left: mini displayport, 3x USB, firewire dummies, power, screen power switch, ethernet, internal sound mini-jack and USB sound card. As you can see, the firewire ports are just a hacked up firewire cable. I thought it would look better than having empty holes, or blocking them. One is going to be a Thunderbolt 3 port in the near future (or maybe the kensington lock is a better location?).

imac g703.jpg imac g704.jpg

What doesn't work:
* It's not very stable in OS X. Photoshop and games will crash it, sooner than later.
* Booting is like playing the lottery.
* Only one of the two USB ports are functioning correctly. One of them drops the connection from time to time.
* Sometimes I get a lot of artifacts on the screen. Doing CPU intensive things (like running installers) seems to especially trigger it. But 90% of the time it is pixel perfect though.

imac g702.jpg IMG_0746.JPG

What does work:
* Ethernet
* USB sound
* One USB 3 port
* Original power button
* NUC and screen are supplied with power from original PSU

I will open this up in probably a couple of months when I have more time. Then I will try to figure out the last quirks. Meanwhile, I will try to get a smooth-running Mac OS X :)
 
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After following RehabMan's guide, I now have a lot more stable system. Photoshop and games runs nicely now. I only get 12000 points in GeekBench though. Probably has to do with the SMBIOS settings, but for now I will just leave it be. I suspect it won't be be optimal until Apple releases a Skylake Mac Mini or iMac anyways.

Untitled.png

The screen noise continues though, but less now. I'm suspecting that changing the IGD Minimum Memory to 64 (vs. 128) and IGD Aperture Size to 128 (vs. 256) somehow helped.

After some days of usage, I noticed that the machine also produces hearable noise, comparable to the sound an old hard drive. It makes this noise when:
  • ... the green artifacts are appearing
  • ... when a lot is happening on the screen (moving windows, video etc)
In additon to this, the inverter itself makes a squeaky noise. I forgot to mention this in earlier posts, but when the machine was assembled as a PowerPC machine with all original components, the screen would make a squaky noise when adjusting the brightness. Now it makes it all the time, as long as something is happening on the screen. It also did this when it was connected to the Macbook Pro under the TMDS cable tests. Does anyone have an idea of what is happening here?

Some finishing points to summarise what is happening:
  • It makes an irritable noise that sounds like a writing hard drive, or the sound of a scrolling mouse.
  • It is most notable when the machine is working hard, and/or when there are moving objects on the screen.
  • It did not make this noise before the mod.
  • The inverter makes a squeaky sound when there are moving objects on the screen. Sounds like a bird.
  • It only used to make this sound when adjusting brightness when original (but with the iMac G5 LCD though).
  • Both these sounds goes wild when the green artifacts are appearing.
 
The green artifacts on the LCD was an issue that I never overcame with my 20" G4 project. Had to swap the HD5000 NUC for an HD4000 model that I had sitting here (which was disappointing) but it fixed the problem and has run solid ever since. I tried absolutely everything.

You've done a terrific job of the mod, albeit you've still got a list of fairly significant issues to resolve. There's no instruction manual with building these projects, and often times, great things are not achieved until great resistance is overcome.

Cheers!

Ersterhernd
 
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