5: Replacing the PSU Fans

I've never been good at leaving well enough alone. I can remember tinkering with some of my toys and plastic models, adding on stuff hoping it would make it "better", with disasterous consequences, of course.

One of the more popular mods for MDDs is to replace the very noisy power supply unit (PSU) fans. Like everything else on the MDD, the PSU fans are very fast, very powerful, very noisy fans whose ability to move air seems to place them out of the range of mainstream PC cooling products. Nevertheless, I thought I'd give it a try.

According to Bits and Pieces, the stock fans within the PSU of the June 2003 MDD are Minebea 2410ML-04W-B60 60 x 60 x 25mm fans, running at 5300rpm, with 25CFM @ 38dB. Compare this with the original PSU fans in the first revision of the MDD: Delta AFB0612EH at 6800 rpm with 38 CFM @ 47 dBA

As with the fan replacement odyssey I went through to replace my stock Papst fan with the Panaflow Ultra, I pored over all of the locally available sources of fans trying to find a fan that could match the Minebea's specs with a lower dB rating. And I thought I found it.



Bigfoot Computers sells a fan which on paper at least, looks like an excellent replacement for the PSU fans in the MDD: Marketed by them under the Bigfoot OEM name (but ostensibly manufactured and packaged by Evercool), they're fans with a machined aluminum frame, instead of the black hard plastic usually used. 5000 RPM with 27 CFM @ 30 dB. Along the way, I picked up something extra: a Sunon 60 x 60 x 15mm "MagLev" KDE1206PHB2 unit to replace the optical drive fan. More on that later.


Errors in Judgement Measurement

I'm sure it's happened to you once in grade school long, long ago: you pick up a ruler, and wonder: do you measure from the zero line, or from the physical edge of the ruler? Some rulers take the added length of the edge into account. Some don't. Some explicitly have the edge equal the zero line. Some don't. So maybe you can imagine my annoyance when I once again disassemble the half of entire inner casing of my Mac and rip into my PSU (using the instructions posted on xlr8yourmac) only to realize that the fans physically do not fit into the PSU. Huh? They said they were standard 60 x 60 x 25 mm fans. The PSU takes standard 60 x 60 x 25 mm fans. What gives?

I measured the length and width of the fans and realized that the Thermaltake fans are indeed 60 x 60 mm in height and length - if you measure 60 mm from the edge of a standard ruler. If you use something like say a ruler where the zero line is not equal to the edge, the fans are actually something on the order of 62-63 mm. This means that two of these fans physically will not fit into the PSU fitting. You could shoehorn them in, but watching the casing of the PSU bulge from the strain really made me nervous. And so, two more 60 mm fans are left out in the cold. But at least it wasn't my fault. I blame the Evercool people. If it says "60 mm" you'd expect it to damn well be 60 mm, right?

Well, at least I had better luck with my optical fan replacement. Andy Davison noted in his own project page that he had found a replacement fan for his MDD lying around; oddly enough it had some problems actually powering up on startup. Bits and Pieces also commented on the lack of a good option for an optical fan replacement. For what it's worth, I think the Sunon fan is a worthwhile fan for someone looking to do this type of mod. Here are the specs: 3800 RPM with 18 CFM @ 31.5 dBA

Compare with the stock fan: Delta AFB0612HHB 60 x 60 x 15 mm, at 4500 rpm with 17.3 CFM @ 35dB

Pretty good overall, I think.

However, as Davison found out, there seems to be some very very slight difference in the dimensions of the Delta fan because the Sunon fan will not immediately fit in its place. This is for two reasons:

a) The fitting has two large metal posts which help keep the fan in place. These posts are larger than the screw holes.
b) The fan itself is apparently too large for the metal shield to fit over; it won't fit so that it slides into the two small locking posts on top of the two large metal posts.

(a) was solved by just drilling through the holes with slightly larger bit. No sweat. (b) took a little more creative thinking. Using a very large drill bit I drilled shallowly into all four of the holes on the bottom (deep enough to make a slightly deep depression), and on the two enlarged holes for the metal posts. The logic behind this was that it would give the posts and the screw holes more room to sink into the fan, giving it the clearance it needed to fit the shield. With some tight pressure, it indeed worked.

After some observations, the fan seems to work perfectly - I haven't had the chance to see the problems that Davison encountered, and I thought I wouldn't, since I made sure to note that the Sunon fan draws less amps than the Delta while using the same voltage.

Delays, Delays

My apologies for not keeping up with things here - I've been sitting on a few posts now thanks to other various things going on in my life. I had a whole post which I've decided not to bother with simply because things have advanced a lot farther with my G4 project since then. I guess you could say it's a perpetual work in progress.

What I plan on doing soon is to put up a sort of MDD buyer's guide to USB 2.0 PCI cards since I've seen questions about them pop up on various forums and list-servs. I also hope to summarize all of my mods in a neat little table, complete with places where I got ideas for them.

I'm backdating these last two posts because I actually did write these back in June or July. Anyway, enjoy.

EDIT: For some reason, I can't seem to access the ability to change time/date for posts in Blogger, so I'll have leave these two posts as they are, for now.

4: Replacing the 120 mm Main Cooling Fan

Quite possibly the most important part of the entire MDD enclosure is the 120 mm fan that in the stock configuration is the single primary source of cooling for the internal components of the Power Mac. Given it's importance, you'd expect Apple to use the most powerful and most efficient type of fan that it could, and indeed it did. In the original version of the MDD released at the end of 2002, the 120 mm fan used by Apple was the infamous Delta AFB1212SHE. At 3700 rpm, it blew out a phenomenal 151.85 cfm, @ 53 dB, making it a screamer - quite literally. In fact, the Delta was quite likely the single most aggravating factor of the first MDD G4s that led to the measures that Apple took to remedy the situation.

Aside from the improved power supply fans, the centrepiece of Apple's solution was the 4212H, made by the European company Papst. Its specs: 3400 rpm, with 108 cfm @ 4 9dB. At this point I can only surmise that Apple came to the realization that the cooling envelope afforded by the Delta could be narrowed down comfortably by using a slower, quieter fan. It would seem then that Apple had apparently overengineered the cooling system on the first MDDs. Circumstantial evidence of Apple "overclocking" the G4 CPUs on these Macs (as originally alleged) perhaps?

The later model FW 400 MDDs released in June 2003 had the Papst fan, as did their OS X-only/FW 800-equipped sister models released earlier. Apple seemed to make a significant improvement to the noise situation (aided in no small part by the replacement power supply fans which accompanied them), but nevertheless, while 49 dB is lower than 53 dB, 49 dB is still 49 dB. Was a better solution out there?

Many 120 mm fan replacement projects that I'd read about on places like MacMod and xlr8yourmac involved the use of quieter fans running at slower speeds (i.e. less rpm's). But of course, with less rpm's comes a lower cfm rating. The prevailing logic behind the use of slower fans was that since the electricity on the 120 mm fan is directly regulated by the OS itself, it seldom, if ever runs at full speed. And yes, apparently my MDDs fans right now are not running at full speed - a lesson I was to learn later on. Anyway, since the fans don't run full blast (or rarely ever do), you can get away with running a slower fan, since at its maximum speed, it would be running at about the same level that the stock fan would when its "regulated". Correct me if I'm wrong, but that's the general impression I got.

I didn't feel good with that. I needed a fan which met if not exceeded the specs of the stock fan (in terms of airflow), but with a lower dB rating. Searches among the usual suspects (Thermaltake, Antec, Vantec, etc.) proved fruitless. But eventually, I found it.



I'd read in some places that a specific fan made by Panaflo (owned by Matsushita, aka Panasonic) was one favoured brand of fan that both ran quiet and ran well. Usually, the "Medium" type had been used, but its specs didn't match up to the Papst. But one type did. Panaflo's "Ultra" type is to my knowledge second only to the original Delta for cfm rating. I'm sure there are other fans out there with better specs, but the Panaflo Ultra was the best I could find in my research. And luckily, it was available at Bigfoot Computers. At 2750 rpm, it puts out 114.7 cfm @ 45.5 dB.

If you order from them (they're a GTA-based outfit, but they'll ship throughout Canada, I think) they'll ask if you want a 3-pin or a 4-pin Molex connector. Get the 3-pin connector. However, if you'll look at the original connector, you'll note it's a two-pin type. That's because standard case fans usually come with three wires: two for power, and one connected to a temperature sensor or an rpm sensor on board the fan. The third pin's connector leads to circuitry on the motherboard which uses the information on the sensors to regulate the power going to the fans. On the MDD, it's not done that way. Power regulation to the fans connected to the motherboard is done via the OS itself, through a .kext file that you can actually modify yourself. Therefore, the third pin isn't needed. Don't worry, though; the 3-pin socket on the fan (which I'll just refer to as the "connector" for convenience's sake) is physically compatible with the 2-pronged outlet on the motherboard (which I'll just call the "plug") - the two pronged outlet is just two wire prongs, and the securing tab is narrower than the fan connector (2-pin and 3-pin connectors and plugs are identical, just that the 2-pin variants are narrower).

In short: just plug it in. But before you do, look at the wiring on the Papst. You'll notice that the "Blue" and "Red" wires seem to be swapped compared to the "Black and Red" wires on the Panaflo. I don't know why this is, but you don't need to change it: here, "Blue" on the Papst is equal to "Red" on the Panaflo, and "Red" on the Papst is equal to "Black" on the Panaflo. This means that you don't need to swap the wires on the connector.

Installation is easy. Open up your Mac, and remove the optical drive assembly just as you would be if you were going to change or upgrade the Super/Combo drives that came with your Mac. Then, lift up the Papst from its socket. It's not even screwed in place; just pull. There are very small and shallow notches on the bottom end of the fan, which correspond to the metal tabs on the fan bracket. If you don't feel like making your own notches by using a Dremel tool or a file, you can just lightly bend the tabs outward to accommodate the fan with some needle-nose pliers. It'll be a very tight fit, but it'll go in. And that's that.

Just for kicks you can experience what this fan can do at maximum speed if you hook it up to an unregulated 4-pin Molex power connector (through an adaptor). I tried it myself and the noise was so loud that it was literally deafening - I could hear it all the way from my room to the kitchen. But I did notice that Temperature Monitor reported an almost 15 degree drop in my CPU temperature...