MDD Dual 1.25GHz Cooling Modification

**DISCLAIMER**

Altering any part of your OS or computer will void your warranty and may damage your computer. These modifications are for educational purposes only and are performed at the owners risk - This site or it's owner are not responsible for any damage caused.

Previous visitors to this site will recall a fan mod I performed that allowed me to manually control the internal fan using a potentiometer mounted near the power button. I was not happy with this solution and started working on phase two of this project. Well, the results are beyond my expectations and have some pictures of the mod performed.

The system (originally a 2003 Dual 1.25MHz MDD FW400) is fitted with an original Apple 1.42GHz module that has been overclocked to 1.5GHz. This module runs a little hotter than the 1.25GHz module not just because of it's higher clock speed but also due to the higher voltage that is fed to the CPU's (1.60V as opposed to 1.55V).

A copper heatsink from a dual 1.42GHz MDD was purchased and replaced the aluminium heatsink that came standard. Initially, I installed a Verax M10 heatsink cooling kit and although this made an improvement, it was not good enough. Verax fans however are a different story. They are the quietest fans around and was able to add 4 new fans to MDD chassis without any increase in noise. I also exchanged the power supply fans (twin 60mm Deltas) with the Verax M11 kit. This made the most difference to the overall noise the MDD produced.

Using the G5 fan design as inspiration, two 65mm Verax fans were mounted on the front grill, under the plastic fascia. These draw air into the chassis past the SCSI drive bays and into the main system fan (original Papst exchanged for a Panaflo). The Panaflo pushes air past the heatsink onto 65mm and 80mm verax fans mounted behind the copper heatsink. These two fans draw hot air straight out the back.

The two 65mm fans on the front grill share power with one of the ATA100 IDE drives. The rear fans source their power from an unused 12VDC connector on the motherboard (near the Airport slot).

A 12VDC PCI fan has also been installed, however at full speed it is noisy. To get around this it shares power with the optical drive fan mounted on the side door and averages approx 6VDC, only increasing when the temperature gets too hot (which is rare now). Temperature Monitor now reports the system temp as approx 54°C down from a much hotter 59°C. Please also see the Applefan.kext mod that was performed.

A replacement MDD door bezel was also purchased ($9US from eBay =) to replace the one I drilled a hole in from phase one of this project. The next step for me is to find a low profile GeForce 4Ti fan that is quiet (this is the loudest component of the system now)

A lot of people have contacted me requesting info on the fans I used. Below are the specs for the stock MDD fans:

* Papst 4212H 120x120x38mm - 3400rpm / 108CFM @ 49dB

* Acbel power supply fans (x2) Minebea 2410ML-04W-B60 60x60x25mm - 5300rpm / 25CFM @ 38dB

I have read that Apple has also used Delta AFB0612EH - 6800rpm / 38 CFM @ 47 dBA. I think these were used in the very first MDD's that everyone complained about and Apple subsequently started the power supply exchange program that offered both AcBel (newer version - possibly like the one in my 2003 MDD) and Samsung power supplies.

* Optical drive fan is a Delta AFB0612HHB 60x60x15 - 4500rpm / 17.3CFM @ 35dB

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and the new fans used:

* 120mm Panaflo FBA12G12H - 2500rpm / 103.8CFM @ 41dB (bear in mind this fan never runs at full speed - usually about 7V or half speed so I would figure about 25-30dB of noise at normal operating temperature)

* PSU fans (Power Supply) - Verax M11 PSU Kit. These contain Verax 65201237-KT 65x65x20 - 3700rpm (variable) fans - I don't know the CFM or dB rating however they move a decent amount of air and are virtually silent due to a three phase motor design. You literally need to concentrate and get right near them to hear them in action. I also used these fans on the front and rear grilles along with Verax 80251231-KT2 80x80x25 3100rpm on the rear.

* I have not yet found a suitable replacement for the Optical drive fan hence the stock fan remains.

Having said all this, the quickest and easiest way to make your MDD quieter is to change the PSU fans - they are the major culprit. The best way to get a cooler running MDD without changing any fans is to replace the aluminium heatsink with a copper heatpipe heatsink from a dual 1.42GHz MDD (Apple P/N 076-0983).