Always use your anti static strap when handling computer circuit boards of any type and store them in anti static bags.
1. Remove the 2 to 3 screws in the back (On some older models the screws were in the front so you would have to take the front cover off. Most just pulled off from the bottom.), holding the side cover opposite the motherboard off.
2. Pull the data cables off of the components as well as the power cables to get them out of the way.
3. Some systems had rails (i.e. Dell) to attach to the hard drive, CD-ROM and floppy drive
to slide in and lock them in place, others have up to 4 screws securing the drives. In the last instance you will have to take the motherboard side cover of the case off to gain access to the screws. Some cases have a separate mounting bracket for the hard drive and floppy drive that will come out of the system by either a latch or screws holding them in place.
Enlight's EN-7650
In this case, the external/internal 3.5" bays are held in with clips mounted to the side of the bay. The bay itself slides out the front for easier mounting of the hard drive and floppy drive. The case comes with rails to mount to the drives in the top 5.25" bays.
4. Next you'll probably want to remove the power supply. One or 2 of the motherboard screws may be behind it. Generally on most standard cases there are 4 screws in the back holding it in place. The proprietary cases may use a different method of securing the power supply in.
5. It's generally easier to remove the memory while the motherboard is in the case, as well as the processor and any adapter cards i.e. nics, modem, video cards. Always use your anti static strap when handling any type of circuit board from a computer.
6. Remove the memory by pushing down on the retaining levers (the white tab looking things) pictured here. Not only will they release the memory, there is a tab on the bottom of the lever that will push the memory out of the slot. Try to push on them both simultaneously if possible. They may be a different color, but work the same none the less.
7, Next come the expansion cards, nics, audio, video etc. Generally in a PCI, AGP slot, held in with one screw on the side. Again, some proprietary cases have their own way of securing the cards in place. Also, the AGP or PCI express card may have a retaining lever at the back of he slot so before you start pulling on either of these, check to see if they do.
8. Removing the processor. In the older machines, you will find processors with little gold looking pins on them. They used thermal grease to aid in the cooling process and sometimes this grease will harden and act like glue between the processor and the heatsink. Intel and AMD had their own ways of securing the heatsink and fan to the processor. Some had levers and hook bracket system, some had twist screw system. You'll find a variety of retaining mechanisms if you work on home user pc's enough. Anyway, back to the thermal glue, ooops, did I say glue, I mean grease. Once you've released the retaining mechanism and if the heatsink still will not come off, try twisting the heat sink. It may be stuck to the processor rather well so you may have to twist a little more than you think. This should release the heatsink from the processor. Next, lift the processor release lever. On the older machines the processor should come right out if the lever is pulled up far enough. On newer machines, a majority if not all, there are probably not any pins on the processor, so another cover has to be lifted from the processor, then it should come right out.
9. Removing the motherboard is a breeze. Usually 4 to 6 screws hold the motherboard in place. There again if it's a non-prop. system.
Laptops, that's whole other ball of wax. Send me a $1000 and I'll tell you how to take your laptop apart.
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