First of all, make sure the computer is turned off, the power adapter is disconnected and the battery is removed.
Both memory modules, wireless card, cooling and and hard drive can be accessed from the bottom.
Remove four screws marked with red circles and loosen two screws marked with green circles. Remove both covers.
Removing DVD drive:
1. Remove one screw (red circle) securing the drive.
2. Push the drive from the case with a flathead screwdriver.
3. Pull the drive and remove it.
Removing hard drive:
1. Pull the hard drive to the right side until it’s disconnected from the motherboard.
2. Lift up the hard drive.
If you are replacing the hard drive with a new one, you’ll have to transfer the mounting bracket to a new drive.
My Aspire 5100 had a 80GB 5400RPM SATA HDD installed.
You can upgrade it to a larger capacity HDD or SSD.
Removing memory modules:
1. Carefully spread latches on both sides of the memory slot until the module pops up at a 30 degree angle.
2. Pull the module out by the edges.
Acer Aspire 5100 has two memory slots. You can install up to 4GB RAM total. Up to 2GB module into each slot.
You should use PC2-533 DDR2-667MHz 200pin SODIMM RAM modules.
Removing wireless card:
1. Disconnect both antenna cables. Grab the antenna cable connector with your fingers and unsnap it from the connector on the wireless card.
2. Spread latches on both sides of the wireless card same way as you did with RAM modules.
3. When the wireless card pops up at a 30 degree angle, pull it from the slot by the edges. Remove wireless card.
Removing cooling fan:
1. Remove two screws securing the fan.
2. Carefully disconnect fan cable from the motherboard.
3. Lift up and remove the fan.
My laptop had a lot of dust trapped between the fan and heatsink. This dust buildup kills normal airflow inside the cooling module and causes overheating. You can blow off dust using canned air.