The SILENT 3rd generation eMac
A modification by Juerg Messer
My trusty old iMac DV (G3/400) had become just too slow for iMovie and MPEG-2 conversion, so it was time to buy a faster Mac. My budget was limited however. I purchased a 1.25 GHz eMac Combo. The LG-Hitachi Combo-drive and the original HD with meagre 40 GB were replaced by a Pioneer DVR-105 (100% Apple supported) and a 120 GB Maxtor HD. Both drives were previously mounted in an external FW housing and connected to the iMac, i.e., no additional costs.
The eMac is not so easy to take apart, I found this web page by Paul Wilkinson very helpful. Note that Paul was disassembling a first or second generation eMac, the design of the 3rd generation is a bit different (e.g. the Harman Kardon sound system is gone!).
Now I had a great Mac for the buck, but I found it to be far to noisy! The old iMac was almost completely silent, because it had no fans at all. The difference to the new eMac was very unpleasant. Something had to be done about it.
I found an interesting remark on Leo Bodnar's web page about eMac overclocking: Leo had installed a variable fan speed regulator in order to reduce the fan noise to a minimum.
The idea was striking but I wanted to have some temperature control, too. After some search in the internet I discovered an Enermax UC-A5FATR2 fan controller in the web shop of a PC dealer and ordered it for CHF 39.- (approx. 25 Euro) + shipping. It is a speed regulator for six fans (2 with speed feed back) and has a display for 2 temperatures (sensor 1 + 2) and fan speeds (fan 1 & 2). It has the size of a 5.25" PC drive bay and is a 3.5" HD mounting rack at the same time. The Enermax has a beautiful silver finish. There exists even a white version that would match the eMac, but it was not available from that dealer.
The HD mounting rack could be easily removed. It was fixed with several screws. The PC board with the 6 knobs for fan speed control was removed, and the cables 1b, 1c, 2a, 2b and 2c were soldered out. Some of the cables were used for the customised wiring. The PC board was put back in place. All cables must be detachable connections, because the Enermax would be fixed on the eMac cover. If it becomes necessary to open the eMac again, I can simply unplug the Enermax connections with the sensor, power supply and fan cable in order to be able to take off the cover.
The fan in the eMac is one of the types with speed feed back (yellow cable). I made sure, that this connection to the eMac would remain intact, whereas the fan will be powered by the Enermax controller. The additional connectors were purchased at a local store for electronic parts. I couldn't find connectors of the type used for the eMac fan, but standard 3-pin Molex connectors could be modified to fit them.
The Enermax comes with a Molex 4-pin y-cable. I used the power supply of the optical drive and fixed the y-cable neatly on the DVD-RW drive with a piece of double sided adhesive tape.
The temperature sensor 1 was fixed on the copper heat pipe coming from the CPU, using 2 cable binders. It was necessary to partly remove the fan to get access. The cable was fixed with another binder and some isolation tape.
The cables were lead to the area at the bottom of the eMac with the many small ventilation holes. Again, note that none of the cables is soldered directly with the Enermax.
The cover of the eMac was put back in place and the memory access hatch was closed. The eMac stand was attached, all cables are hanging out of the right ventilation opening of the stand. Two layers of thick double sided adhesive tape are fixed in stripes between the ventilation holes in the eMac cover. When the Enermax is fixed, air can still stream in through the gap between the Enermax and the housing. The Enermax was then fixed, but better do that when the eMac is back on your desk, to be able to fix it accurately aligned with the housing.
Now I can adjust the Fan Speed 1A knob to regulate the fan to a pleasant noise level, while I see the impact on CPU temperature on the display (Temp. F1). The fan speed is not displayed although it is supposed to be. I don't know the reason, but I don't care. It doesn't matter. I have no Apple Hardware Test CD for the eMac, so I don't know if the internal fan speed feed back is still working or not. Note that the speaker grills have been removed to further improve the sound quality. The grills were pulled out using a modified paper clip. Make sure nobody sticks its fingers into the speaker membranes, e.g. little children
Another note about the sound quality: The eMac is now silent enough to actually be able to enjoy music. The quality of the internal speakers in the 3rd generation eMac is inferior to the iMac DV's Harman Kardon speakers. The new eMac speakers sound dull. If I can spend the money, I will buy JBL sound creatures, but without the fan modification it would be waste of money.
Have more fun with your eMac!
Addendum 1: After 2 years and 3 months of operation, the 120GB Maxtor DiamondMax Plus harddisk has died. Fortunately it didn't do that immediatley but within a week, so I was warned and made a backup in time. I have now replaced the harddisk with a 160GB Samsung. Since I am wondering if the reduced ventilation in my eMac has shortened the life span of the Maxtor HD, I have made the following modification when I replaced the HD. The second temperature sensor was fixed on the new HD with adhesive tape. I do not reduce the fan voltage below 50% now (instead of 33% to 40% before). Now I will observe, how the HD temperature behaves under different operating conditions.
Addendum 2: After another 2 years and 2 months of operation, the 160GB Samsung harddisk had errors that the harddisk utility could not fix. Formating and overwriting with zeros didn't fix the problem, so I had to replace the HD again. This time it is a 160 GB Western-Digital. Since I had to disassemble the eMac for the HD exchange anyway, I thought it is a good opportunity to overclock the CPU at the same time. By the way, the memory was increased to 1.5 GB before (2 GB are possible), when the clock battery had to be replaced. Overclocking is a bit of work: With the 3gen eMac, the five PLL encoding resistors are located on the front side (under the optical drive) as well as on the back side of the mother board, so that you must disassemble the eMac as far as it is necessary to access the HD. Fortunately the resistor combinations have been published here and here. I have expanded the table for the useless 1.17 GHz combination (I have spontaneously found out that setting by forgetting to remove R270 when I wanted to set 1.42 GHz). Note: According to some forum postings higher CPU clock speeds than 1.42 GHz are incorrectly displayed in "About this Mac"!
1.17 1.25 1.33 1.42 1.50 1.58 1.67 1.75GHz<br /> R658 (back side) + + - + + + - -<br /> R270 (DVD side) + + - - - - + +<br /> R673 (back side) - + + - - - - +<br /> R275 (DVD side) + - + + - - + +<br /> R689 (back side) + + + + - + - -<br />
As usual, "+" means either resistor or solder bridge is present and "-" is an open contact or removed resistor