Yesterday my old G5 Apple iMac started to crash and have screen corruption with windows appearing to freeze and then leave parts behind when moving around. After a hour the computer was crashing as soon as it booted and the startup logo developed distortion and lines across the screen and ended up with the display being completely unusable.

After removing the cover on the iMac I found that 4 of the capacitors on the main logic board had expanded and blown which were located in the areas circled below.

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From new my Mac Pro tower has had an annoying high pitched squeal or whine when moving windows or scrolling windows on the screen.

The sound is not there all the time but only after the machine has been on for a few hours so it had to be heat related.

After spending an hour or two tracking down the sound it was coming from the Nvidia 8800GT graphics card which is fitted as standard into the Mac Pro’s.

Other blogs and forums suggested that the noise is caused by the inductors on the graphics card resonating when under load and needed to be fixed down.

After removing the graphics card and taking the heatsink cover off which was held on with cross head screws, I found several large inductors on the board.

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Aluminium iMac Hard Drive upgrade guide

Upgrading the internal hard drive in a 2007-2008 Apple iMac to 1.5TB

The following guide provides step by step instructions on how to disassemble and upgrade your Apple iMac 20" or 24" models.

Tools required:
T6 Torx Driver and T9 Torx Driver
Suction Cups for removing the glass front panel - These can be obtained from many DIY shops or online for less than £10
Philips Screwdriver for removing the memory cover.

New Hard Drive. I used a Segate 1.5TB SATA 7200 rpm model which was £140

http://vimeo.com/moogaloop.swf?clip_id=2252036

Below is a link to a HD video of the work involved in the upgrade:

Apple iMac hard drive upgrade from Brian Dorey on Vimeo.

Please note this is not an official Apple guide so proceed at your own risk!

1. Remove the memory slot cover from the base of the machine.
2. Using the suction cups carefully place on the glass screen cover and remove the glass panel. Place somewhere safe and clean.
3. Remove the torx screws from the front panel surround on the edge of the LCD screen (some of the screws are different sizes)
4. Lift the screen away from the main chassis and life up and over above the computer
5. Remove the screws holding the LCD panel to the chassis
6. Remove 2 screws from the LCD connector and remove the connector from the graphics card
7. Carefully life the LCD panel from the bottom to expose the 4 small connectors for the backlight. Mark the connectors with a marker to aid reassembly and disconnect the connectors
8. Lift the panel clear of the chassis
9. Remove the hard drive temperate sensor and place to one side
10. Unclip the hard drive from the chassis. This plastic bracket can be a tight fit so some force is required to remove it
11. Remove the power and SATA connectors from the hard drive and remove from the chassis
12. Remove the screws holding the plastic clip from the hard drive and the 2 mounting pins from the other side of the hard drive
13. Fit the clip and pins to the new hard drive
14. Reconnect the power and SATA connectors and clip the new hard drive back into the computer chassis
15. Refit the LCD screen and reconnect the 4 small backlight connectors
16. Place the LCD panel flat on the chassis and reconnect the screen connector and refit the two small screws
17. Refit all the screws from the edge of the LCD screen
18. Refit front panel and take care not to trap the small cable at the top of the screen
19. Refit all the front panel screws in the same order as they where removed (some of the screws are different sizes)
20. Clean any dust from the LCD panel and the front glass panel using a soft screen cleaning cloth (don't use compressed air as this often leaves propellant on the screen which is very hard to remove)
21. Remove the suction cups from the screen and clean the glass.
22. Refit the memory slot cover on the base of the machine.

Next you need to reinstall OS X from your operating system disks and then your upgraded iMac is ready to use!