Upgrading Apple eMac

eMac 1.33GHz / 1GB / 160GB / DVD±RW / OS X 10.3 for £927

I met someone who looks a lot like you
She does the things you do
But she is an IBM...
              ELO, "Time", 1981

Original eMac - Out Of The Box

This eMac has been bought brand new at the end of December 2003 for £499 from PCworld as an end of line discounted model. Its original configuration was:

Apple eMac
Mac OS X 10.2.2 (Jaguar)
G4 800MHz processor
40GB hard drive
ATI Radeon 7500 32MB Graphics
Internal 56K modem

Apple has three ranges of eMac:

- "original" (1st generation) eMac. It has been made in 700MHz and 800MHz versions, uses GeForce2 MX graphics, 7455A G4 processor with 100MHz system bus and has silver memory access door at the bottom.
- "new" (2nd generation) eMac. Has 800MHz or 1GHz 7445A G4 on 133MHz system bus, ATI Radeon 7500 graphics and white memory access door. I have 800MHz model.
- "the latest" (3rd generation) eMac introduced in Spring 2004. 1.25GHz G4 on 167MHz system bus, ATI Radeon 9200 graphics. I know nothing about that model's potential yet.

Both "original" and "new" eMacs are excellent value computers (especially after "the latest" model introduction) but have slightly different internal construction and upgrade potential as we will find out later. This one is a "new" 800MHz model.


Putting in as much memory as you can should be the first thing to do to a new Mac. Any eMac RAM can (and should) be upgraded to 1GB. Almost any pair of 512MB PC133 SDRAM will do.

After installing the memory run Apple hardware diagnostics CD-ROM included with your eMac. I have seen eMac successfully starting OS X or OS 9 and running perfectly normal but failing to even boot from diagnostics CD (it had 512MB PC133 SDRAM from PNY Technologies) - eMac reported memory access error and went to Open Firmware prompt. This could have been caused by wrong data in EEPROM chip on the module.

Anyway, to be on the safe side make sure you can pass all tests on diagnostics CD.

Hard Disk Drive

Original 40GB hard drive has been replaced with retail version of Maxtor's Ultra Series 160GB drive (it has 8MB cache) and then configured as one 160GB partition. Both OS 9.2 and OS X recognize full 160GB (worth mentioning, since earlier models, e.g. some G4 towers have a limit of 128GB per disk.)

Paul Wilkinson has excellent instructions on eMac disassembly ("original" model) in case you decide to do it yourself. I have a "new" model that is just slightly different inside, for example it does not need taking main logic board out to replace the CD drive. In any case I recommend using official Apple Service Manuals as a primary source of take-apart instructions (see below.)

New hard drive is literally silent as most of modern drives and increase in disk access speed is very noticeable! Xbench disk test result is 120 (original 40GB Maxtor result was about 70.) I have placed original 40GB drive in external Firewire/USB case so it is not wasted.

It is interesting to note that eMac has two independent IDE channels (like an average PC) even though it uses only two drives - hard drive on one of them and CD-ROM (or CD-rewriter) on the other. Flat panel iMac, however, has both drives on the same (and only) IDE bus. I guess eMac simply got lucky because two drives are physically located on the opposite sides of the motherboard! That means that it is possible to connect up to 4 IDE drives to the eMac (but not to flat panel iMac). To verify this theory I have connected 3 internal IDE hard drives at once: one original and two, attached to a long IDE cable running from CD-drive logic board connector. And it does work! All three drives were set up for CS (CableSelect). One comment though - I have used external power supply for two additional HDDs to avoid overstressing eMac's power supply - I am not sure of its rating.

Useful hint: Modern hard drives have an internal feature called AAM - Automatic Acoustic Management. It allows to trade few percents of drive's performance for nearly silent operation by eliminating head movement noise. Apple supplies Macs with drives set for silent operation but most OEM hard drives are sold set for maximum performance mode. This utility allows you to control the drive's AAM feature. It works only on internal drives in OS 9 but not in Classic. However if you can not boot into OS 9 there is a way out - AAM feature is "sticky", so you can put the new drive in another Mac or a PC and set its AAM parameters there. There are quite a few AAM utilities for PC.

Useful hint: New Maxtor drives perform internal test when the data just written to the drive is read back and its integrity validated. This test is only active during first 10 power cycles and slightly affects drive performance. After that it will be disabled and drive performance will reach its maximum.

Mac OS X 10.3.2 (Panther)

I have upgraded OS X from 10.2 Jaguar to 10.3 Panther and it works as advertised. More information is available elsewhere.

66% Processor Speed Increase

This is the sweetest and most difficult part!

"New" eMac CPU model is PowerPC 7445 - low voltage version of 7455 used in the "original" eMac. It generates only half the heat of 7455 running at the same speed but does not support external (L3) cache. However it is virtually impossible for any software to tell them apart so it is usually reported as 7455. This eMac's 800MHz CPU already runs at 133MHz bus clock so the only way to increase the speed is to change the processor internal PLL multiplier. It is controlled by a set of miniature resistors on the main board within highlighted area:

They are labelled as (top to bottom) R1506, R1509, R1512, R1515, and R1518. In fact they are not resistors per se but surface-mounted jumpers or resistors with zero value or simply pieces of wire in the form of resistor for easy automated board mounting. To change the multiplier settings it necessary to alter the configuration of these resistors. To remove the resistor it needs to be heated up from both ends by a soldering iron with a flat tip. Extra solder is very useful here - it "wraps" the component around and facilitates heat transfer. Excessive solder can later be removed by applying some flux.

I have found that instead of trying to connect two pads with reused or new resistors it is much more practical to use some extra solder to simply create a "bridge" between them. You would appreciate the difficulty of soldering resistors back when you see the size of removed resistors here.

Use the following table ("+" means the pads should be connected either with a jumper or solder) and the picture (see also datasheet page 47). It applies to both, 800MHz and 1GHz "new" eMacs.

Jumper  800MHz   866MHz   931MHz   1.0GHz   1.066GHz   1.132GHz   1.2GHz   1.266GHz   1.333GHz   1.4GHz 
R1506 - + + + - + + + - -
R1509 - - + + - - - - + +
R1512 + + - + + - - - - +
R1515 - - + - + + - - + +
R1518 + + + + + + - + - -


I was expecting that the last samples from the end-of-line model might use overspecified (underclocked) CPUs. And yes, the result is more than surprising:
No problem with running that eMac at 1.33GHz with no modification to existing cooling subsystem! And yet no problems with passing tough CPU stress tests!

It has run variety of applications under 100% CPU utilisation for many weeks in a row without any problem - therefore I consider the system stable. Recently I have tried increasing the speed up to 1.4GHz - the Mac booted and seemed to work OK but crashed after about 5-10 minutes under intensive load. I guess that is where better cooling system might be needed. I am happy with 1.33GHz and I did not have any single problem at that speed.

The logic board has an option to adjust CPU core voltage but I did not try changing it. There seems to be no need for it.

Xbench benchmark result at that speed is around 140. Full score...

As a test I have installed Yellow Dog Linux for Mac and recompiled its kernel about ten times. Kernel compilation is very demanding task for CPU and RAM and usually causes kernel panics on bad hardware. This eMac had no problem and I went back to using OS X Panther.

Sidenote: Sometimes I hear speculations on how much overclocking might affect the lifespan of the CPU. Typical statement is... "I don't know anything about it but I think it will kill my CPU real quick." A scientist by education, I went on and pulled together some actual figures based on Motorola research. Here they are:

The theory:

1. Motorola specification says that junction-case thermal resistance for 7445 is 0.1°C/W. Let's add another 0.1°C/W for thermal grease layer. Peak dissipated power for 7445 at 1.33GHz is 26 Watts. That results in maximum temperature drop between bottom of the heatsink and chip die of about 5°C. Maximum junction temperature limit during guaranteed operation is 105°C. All the above means that heatsink can be as hot as 100°C and CPU will still be within manufacturer specifications. Water at sea level boils at 100°C.

2. Since in theory chips can fail at any temperature and clock speed, CPU manufacturers research and keep that statistics. Let's see Motorola figures. Failure rate at 105°C junction temperature is 135 failures per 109 device hours (that is 114 thousand years.) Which is on average about one failure per 845 years. If you drop junction temperature to 65°C you will do about 15 times better - one failure per 11.5 thousand years. Why 65°C? Because that is what normally feels to touch as "burning hot".

Short summary: on average you can boil water with your CPU continuously for about 845 years until CPU fails (Maybe electric kettle manufacturers should learn something from Motorola?) Or you can boil it with 100 heatsinks at the same time and only one of those CPUs will probably fail in about 8 years. This is extreme of course! Nobody runs CPU at 100°C simply because any reasonable heatsink will bring it to much lower level.

The practice:

I have never seen a credible report on Mac CPU irreversibly damaged by heat during normal operation (I don't consider cases when people forget to attach heatsink at all.) Overheated CPU locks up or crashes but starts functioning normally again when it has cooled down. By the way I had two broken kettles over last 8 years...

CD±RW / DVD±RW Drive

I have replaced original CD-ROM drive with retail SONY DRU-510A DVD±RW rewriter (£99).
Panther 10.3.2 does not have native burn support for that drive so we need to do some extra work apart from fiddling with screwdrivers.

Open Applications > Utilities > Terminal and type

sudo mkdir -p /Library/DiscRecording/DeviceProfiles/
provide your current password when prompted. This will create /Library/DiscRecording/DeviceProfiles/ directory on your hard drive.
sudo means superuser do. mkdir -p means make directory and create all necessary intermediate directories as required.

Then download this file and place it in the above directory. When moving file over you may be asked to authenticate yourself and provide your password again. That's it! You don't even have to reboot.

Now all iApplications will have native burn support. You can burn CD/DVDs from desktop and erase CD-RW and DVD±RW with Applications > Utilities > Disk Utility. And, yes, iTunes burn too! I have successfully tested iDVD with that drive as well.

Useful hint: You will have to remove drive's tray front panel for installation (just the part that is clipped to the tray itself.) This will create some extra space between the tray and eMac's hinged CD door. When ejecting, the tray touches the door having already gained some speed and when retracting it allows the door to close long before the tray has stopped. If you want to minimise the noise from loading and ejecting CDs, attach some spacers to the front of the tray to eliminate that gap. Use your imagination! You can reuse original eMac's drive black plastic strip attached to the tray's edge but it is not thick enough. I have used self-adhesive rubber feet from some device.

Dual Screen

Apple VGA display adapter (£15) allows to connect an external monitor. Even though Apple limits its use only to mirroring the main screen, it is possible to lift that limit and run dual-screen configuration using AppleScript firmware updater from Klaus Rutemöller. It is really nice to have that much screen space! The screen on the left is 19" Samsung SyncMaster 191T running at 1280x1024 resolution. Notice how Finder window is stretched across both screens. Imagine squeezing contents of both screens into eMac's screen and you will see what I mean! Also you can watch DVDs in full-screen mode in the main display and still do something useful on the other!

Useful hint: Most probably you would want to use your external screen as the primary display due to better quality and bigger size. To do that you would need to open System Preferences, select Display pane and click Arrange tab. Then drag the menu bar from one little screen to the other. That's it!

Getting Rid Of Fan Noise

This is one of the most popular modifications! eMac has just one fan and it is reasonably quiet by general computing standards (have you ever been in a large datacentre?) but compared to iMac it is rather loud and never slows down. Some tried to replace the fan but this is quite demanding process.

Having had vast experience with different computing hardware I was expecting serious problems altering the cooling of a system with integrated CRT using just one fan so I started to approach the problem from a distance by streamlining the airflow inside the case in anticipation of improving cooling efficiency and then slightly dropping fan RPMs but excellent news is... it all turned out unnecessary. The radical solution is to simply drop fan speed without changing anything else at all! First I've tried lowering the fan's supply voltage (+12V) by inserting inline resistors but then just went out and bought a variable fan speed controller for PCs from the nearest shop. It is cheap and available almost everywhere. To cut the story short - you can slow down fan to the point where you cannot even hear it rotating and eMac would not care at all. Remember, this is with overclocked CPU, fast hard drive and 1GB or RAM and under day and night 100% load. If this is not the best computer hardware engineering, than what?!

Use rather long wires to attach the regulator so that you can initially keep it outside the case to adjust settings on the run, then after you are happy with eMac performance and noise level, mount it permanently inside - there is enough space for it under the fan bracket.

Apparently this idea is not new and is very well described here by French (translation).

Useful hint: The fan has the rotation speed sensor (the third wire apart from GND and +12V) and fan speed can be tested during extended system test if you ever boot from Apple hardware diagnostics CD-ROM. Reasonably enough due to reduced RPMs the extended test will fail with error code 2FAN/2/1:MLB. The workaround is... just ignore it.

Other Nice-To-Haves

Replace cool looking Apple mouse with practical Microsoft Wheel Optical USB mouse. It does not need drivers in OS 9 / OS X, the wheel scrolls windows up and down, right button brigs up context menu, and it works on almost ANY surface unlike Apple's mouse. Microsoft shines here (literally) while Apple doesn't - there is no native OS X support for swapping mouse buttons if you are left-handed.


It is a hell of a Mac for the money!

Few Words Of Caution

I hope you have enjoyed reading these quick notes (at least you've made it that far) and have not yet started to take your Mac apart! I have to say that if you want to do upgrade like this on your own, please think first and then act. Please...

- have a plan before you start
- proceed slowly and carefully
- use right tools, stop and visit nearest hardware store if you feel that existing tools are not good enough
- don't throw screws and parts around or mix them up. Maybe take notes as you move forward
- let high voltages inside eMac dissipate after you switch it off (30 minutes or so)
- touch eMac's metal frame first before touching any internal component with your hands, screwdriver or soldering iron
- if you are not sure that you can make it, then stop and put everything back... Come back later - there is no rush
- get someone to help you, maybe a friend with a PC or other electronics experience
- This is THE eMac overclocking resource.

Update: I have been running this eMac for a long time and had no stability issues. It was my primary computer at home for some time and was used a lot. Over the time I've received feedback from people who have successfully performed the upgrade - they run their eMacs at anything from 1.2 to 1.5GHz. 1.2GHz seems to be always achievable. Most people settle on 1.33GHz for 800MHz models and 1.4GHz for original 1GHz eMacs.

Good luck!

Assorted Pictures

They have been taken three weeks after the upgrade because many people were sceptical about processor being in fact 800MHz.
Of course it was not necessary during the initial upgrade. Heatsink has been cleaned and refitted with a new layer of high thermal conductivity grease. Notice how small actually heatsink is!

© Leo Bodnar, originally posted 4th January 2004.

Assorted Links...

...to point you further in that direction if you are interested.
Links appear here as soon as I get the information:

Apple Manuals (very slow downloads) - Official take-apart instructions

Headless eMac
eMac 700MHz overclock - Brent Garner's instructions for 700MHz and 800MHz GeForce2MX graphics eMacs
iMac 800MHz 17" overclock - Tony Shadwick
iMac G4 (USB 2.0) overclock - Alexander Thomann
Silent 1.25GHz eMac - Juerg Messer

iMac 800MHz 15" logic board photo - top  bottom 

User reports on hard drive, CD, DVD upgrades in Macs at xlr8yourmac.com
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