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| Unreal G4 Mark II |
| Written by Chris | ||||
| Friday, 01 September 2006 | ||||
Yes, on first sight it looks similar to my first post from two years ago, the Unreal G4 that I sold some time later to be replaced by a G5. But as I am involved in quite a many little trades and deals with used Macs, I soon ended up with enough leftover parts to build one more custom MDD, which would have to turn out better n badder than the first unreal one. 
Speaking of unreal: the speakerhole-fan with its unreal logo was a must. It allows the use of lower RPM PSU-fans, thereby eliminating quite a lot of total noise while still keeping the power supply cool and happy. I won’t go into details about that anymore. However, the basic concept of this Mark II Mod differs quite a bit from the original Unreal G4. 
This mod requires some irreversible case modification due to some serious chopping around. The initial idea was simple enough indeed: provide all hardware components with a constant fresh airflow and be confident that the heat then finds its way out of the case all by itself. The airflow must follow a rough direction to prevent hot air from being recirculated again. This is actually the most important thing to keep in mind. 
The one major candidate for direct fresh air is of course the CPU-Heatsink. I picked up my old idea of a fan mounted in place of the harddrive-bracket. But unlike the original unreal G4, it now pulls the fresh air in from underneath the case and blows it right across the heatsink. And this is how it can be done. 
Many of you guys know how to cut and bend steel and give it the right shape. Do it according to your skills, tools and patience. The result must be to blow the fresh air from the Mac’s underside right into the core of your G4case. The grille at the G4’s backside in this section has to be sealed. Since this whole grilled surface will exhaust the heat, you do not want to pull the hot air right in again. 
On the first test run using a very low RPM fan (moving only 11CFM), temps never exceeded 50˚C. I later exchanged it with a stronger fan connected to the mainboard, so it ran quietly enough on 4.8V and had enough power reserves should the need for more instant cooling arise one day. In order to get a constant airflow through the case, there had to be some more active air intakes. One perfect location is right under the front harddisk-bracket. A 92mm fan (currently one cheapest no name model running low at 7 volts) fits right in there. A little more tricky to do was the glassfiber duct for one 80mm fan at the front bottom where that polished grill-mirror thing has been drilled away and out. Be careful, there is not enough space here left if you want to fit in the hard drives while still being able to mount the front cover without modification. 
Again, I am confident that this could be done in a much more proficient way but you get the idea. The fan used right now is some supersilent 12V thing, moving just a tiny bit more air than nothing at all. 
’Tis interesting to see that even with this minimal but constant airflow, temperature conditions in the whole MDD case improve greatly. Gone are the days when you felt like opening an ovendoor when looking into the MDD after some hours of use. The stock 120mm case fan, shovelling the air around in circles inside the case has vanished. There was no use for it anymore at all. And it was much too loud anyway. Of course, my modified machine still recirculates a cartain percentage of air through those little vent holes in the left side of the metal case. The 12cm fan will pull this air in again. I thought this would prevent any dead spot inside the case where heat could accumulate, but actually it’s hard to tell and remains open to further investigation. And now I tell you a secret: The optical drive bay fan, mounted in the fold-down door and connected to the regulated mainboard fan connector, does not only provide a slight blow over the DVD-RW, but does in fact move some air underneath the logicboard. Anyone ever looked at an MDD logicboard’s underside? Yes, there is one tiny heatsink and the casedoor even provides an opening with some minimal airflow for it! So I figured the small optical drive fan was still needed and I found a suitable one, thinner, quieter and a little more powerful than the stock delta. One more thing about the speakerhole fan: luckily enough I found an extra thin 80mm fan in only 15mm thickness (some chinese made thing I picked up in korea). This means I can still use full length PCI and AGP cards such as the Geforce 4 Ti. 
the loudest part was Geforce4Ti’s blower. I soon found a matching Zalman VGA-cooler in a local PC store. It did cost quite some money, but it’s really worth. Its fan currently runs at 7V.  
The Geforce 4 Ti is probably the fastest ADC-equipped, OS 9 supported card for the G4; I was lucky to get one for a reasonable price. I want the native ADC-connector, I want full OS 9 Support and I want a card fast enough for UT2004. Is there any other choice left? And, yes, one ram slot is blocked by the vga-cooler. Who cares? The MDD can handle only 2GB DDR anyway. 
CPU wise, I was first running a Dual 1GHz, but later replaced it with a Dual 1.42GHz module. This required some modification of the aluminium heatsink’s bottom due to the CPU-cards slightly different layout. 
Average CPU temps were instantly raised by 10˚ due to the 1.42’s higher power consumption! For that reason, I replaced the previously used constant speed fan with a much stronger Japanese brand fan, connecting it to the logicboard. I just feel safer when software (in OS X) or firmware (in OS 9) handles the fanspeed according to actual temps, because I tend to walk away leaving the Mac running unattended for days. 
Since I had not planned using a 38mm thick fan, it first collided with the heatsink when closing the case. Oh well. I have got used to chop things off already, so I just made the heatsink a little smaller. Sure this is not the ideal solution, but it works fine for me now. Anyone who attempts doing this mod should do himself a favour and leave enough space for the bigger size fan from the beginning. Correcting it later is quite a pain in the head… 
Noise? A little whisper when positioned on the desktop but it blents perfectly into general background noise (e.g. my fridge) when placed under the table, especially when the G5 next room is spinning up its fans. There is no pitch or frequency in the G4’s noise (something that can be unnerving even at low dB). My Maxtor boot drive is mounted in what’s left of the upper 5.5” bay, the remaining hard disk-bracket underneath can hold 2 more disk drives, means there is still the option to install a fast raid-0 or a terabyte of storage. Design Honestly, I was a bit stuck when choosing the G4’s look. Initially, I had planned creating a MadMaxMac, all rusty and stuff, but the steel case is not prone to corrosion at all… The design can be done in every possible variation. you can even have it look like stock, keeping the speakerhole small. However, I didn’t want it stock and I didn’t want it painted. I tried a full transparent look by cleaning away the cover’s paint with 98% alcohol that turned out being impressingly ugly. 
After some consideration, I also swapped the acryllic handles with the G3’s milkywhite ones. They are not as sexy, but since they are a bit more elastic and have a stronger feel than the acryllic ones, I preferred using them. Now this Mac blends in wherever it is and doesn't show off, except here at MacMod.com!
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