Your body carries Static electricity. Static WILL fry out, (Short Circuit), the delicate hardware components inside a computer.
Relieve your body of Static BEFORE reaching inside, your unplugged from power computer.
Computer on a table, computer Unplugged from power, computer case open;
TOUCH an unpainted surface, of the metal frame of the open computer case.
This action will relieve your body of Static.
IF you leave your computer in the middle of working on it, be SURE to Touch the metal frame again, upon your return.
HP Support > Compaq Presario SR2013wm > Main Support page,http://h10025.www1.hp.com/ewfrf/wc/product?product=3300335&lc=en&cc=us&dlc=en&lang=en&cc=us
How to > Adding / Replacing hardware > Opening the PC case,http://h10025.www1.hp.com/ewfrf/wc/document?docname=c00595250&tmp_task=useCategory&cc=us&dlc=en&lang=en&lc=en&product=3300335
1) Is the computer dirty inside?
If so it needs to be cleaned. Use a can, or two of compressed air for computers. Make SURE the Processor fan, and finned Heatsink under it; are clean.
2) Remove all Ram Memory module/s. ('Stick')http://h10025.www1.hp.com/ewfrf/wc/document?docname=bph03886&tmp_task=useCategory&cc=us&dlc=en&lang=en&lc=en&product=3300335#N406
Clean the gold plated contact pins with a pencil eraser.
If you are using an eraser on the end of a pencil, and not a solid eraser, refrain from letting the metal band of the pencil, touch the gold plated contact pins.
General example of a desktop computer Ram Memory module,http://en.wikipedia.org/wiki/File:Generic_DDR_Memory_%28Xytram%29.jpg
Everywhere on the ram memory module, EXCEPT the gold plated contact pins; is the BODY.
The Body is coated with a see-through protective plastic.
Handle the Ram Memory module by the Body.
Rub the eraser up, and down on EACH contact pin. BOTH sides.
After you have finished cleaning, it may seem like you have done nothing at all.
The contacts may not be bright, and shiny.
I assure you that you have. Doesn't take much 'corrosion', to make a bad contact surface.
(Gold isn't supposed to corrode. Used word to try to explain)
When finished cleaning use air to remove the eraser dust. You can use a can of compressed air for computers if available, or air pressure from your mouth will be sufficient.
For additional questions please post in a Comment.