Up to 8GB of DDR3 Sdram ram memory that is SO-DIMM for laptops, and 1066MHz.
That is PC2-8500 that is SO-DIMM
There are TWO Ram Memory slots. EACH one has a maximum amount of 4GB.
Total Maximum Amount of Ram Memory is 8GB.
IF, just one Ram Memory module ('Stick'), is to be used, it is placed in ram memory Slot 1. (DIMM 1)
(The Processor reads what is in Slot 1 first. Cannot have ram memory in Slot 2, and not Slot 1 also )
No that's okay Acer/Gateway/eMachines!
I have access to the SERVICE MANUAL, bahahahaha! Your lack of info doesn't bother us...........http://www.manualowl.com/m/eMachines/E644G/Manual/258030
This is a PDF file. Scroll the page down using the scroll bar all the way to the right, until the top header of the PDF file reader shows.
To the immediate right of the number 216 at the top, is the Page Down Arrow.
To the left of the number 216 is the page number box.
The PDF reader page numbers do Not match the actual manual's pages.
Put your mouse cursor in the page number box.
Backspace the 1 out.
Type -> 95
Press the Enter key on your keyboard.
(In the Top header is also the controls for view size.
To the left of the page number box is a Slider that is a blue 'Dot'.
Left-click on the blue 'Dot', hold the left mouse button down, and drag it to the left to Decrease the view size.
To the right to Increase view size )
Under the bold subheading - Prerequisite, click on the blue -
Base Door removal
Bottom of laptop facing you, open Battery Compartment to the Top, away from you, the Base Door is at the bottom.
Rectangular cover that has two Philips screws holding it on.
One screw at the Top/Middle, one screw at the Bottom/Middle.
Remove these two screws, do not lose them. (Double-sided sticky tape to table, and stick the screws to the tape )
Remove ALL power. Remove the AC adapter (Charger), and Battery.
To go on;
This is a general example of a laptop SO-DIMM ram memory module,http://en.wikipedia.org/wiki/File:1GB_DDR2_SO-DIMM.png
Note the Locating Notch on the bottom, and the two Side Notches on either side.
The Locating Notch at the bottom, lines up with a Locating Lug in the bottom of the ram memory slot.
For this reason it can ONLY be installed in one direction.
There are spring clips that 'snap' into the Side Notch/es.
The top of one spring clip is eased to the outside of the laptop.
Now ease the other spring clip to the outside.
Once both spring clips are freed from the Side Notches, the ram memory module should pop up a little.
(Sometimes you have to keep one spring clip, held out with one hand, and with the other hand move the other spring clip out )
Remove the Ram Memory module, at almost the SAME angle as it is now. Slightly tilted.
DO NOT bring the Ram Memory module straight up, or you will damage the gold plated contact pins of the Ram Memory module, and also the contact pins down in the ram memory slot.
Notice how ram memory in Slot 1, (Slot A), is on top of the ram memory module in Slot 2. (Slot B)
If you have two ram memory modules installed, you have to remove the top ram memory module, first. (Slot A)
Again, if you are just going to use ONE ram memory module, it goes in Slot 1 (Slot A)
Look at the ram memory slot, and the Locating Lug in the bottom, and/or observe which way the Locating Notch on the ram memory module was, before you took it out.
Line the ram memory module up with the Locating Lug.
Install it at the same angle roughly, that you took it out at.
Once in the correct position the spring clips 'bumps', will snap down into the Side Notches, of the ram memory module.
(Click / Click)
Reinstall the Base Door.
Reinstall the Battery.
Attach the AC adapter (Charger), and plug the AC adapter into power.
(ALWAYS plug into the laptop FIRST, then plug into power. Otherwise a power surge could happen, and burn out electronic components in the power section of the motherboard)
WAIT 1 minute, turn the laptop on. BIOS will recognize the ram memory. You're done.
For additional questions please post in a Comment.