MacBook Pro Beeps Three Times on Start-Up

Question

I recently got a used MacBook Pro from my uncle, so I would have a laptop for college. When I start it up (with a new Snow Leopard install disc), it beeps three times. I've looked this up to determine it's an issue with the RAM, so I bought a new 8GB stick from OWC, and installed it. It is still beeping three times on start-up.
When I boot without the start-up disc I just get a flashing folder with a question mark in it (no OS found, that's why I need the install disc).
It no longer has a service contract (from early 2011).
Help on why this thing is beeping at me would be appreciated.

Answer 1

What kind of RAM is in the second memory chip slot?
Usually these are sets of two, and matching is best.
•Maximum Memory    16 GB (Actual) 8 GB (Apple)
•Memory Slots    2 - 204-pin PC-10600 (1333 MHz) DDR3 SO-DIMM
Rarely would anyone install only one RAM chip, and
when a computer such as yours can use say, 8GB a
credible path to 8-GB would be two 4-GB/matching.
Or if you had a good 2 or 4 GB chip, it could occupy
the second slot for a slightly uneven workable match.
{What were the two RAM chips removed from the MB/Pro?
...At this point, I'd venture to guess they probably are OK.}
And there can be an issue even with RAM of the same
spec numbers, some of them for a PC or iMac will not
do well in an Apple portable, though of similar spec.
However I get the impression there is a hardware failure
at some other point, to include a bad hard disk drive..
A diagnostic is recommended since most usual startup
sequences do not work; so troubleshooting isn't possible
in the sense that most users would be able to at home.
Also a retail Snow Leopard 10.6 DVD should be of a
newer version than the one your MacBook Pro shipped
with, since the original system discs would have been
one of two Snow Leopard versions. However being
unable to boot from the DVD and have it run the Mac
the issue may be a logic board failure, if not RAM.
•Original OS    Mac OS X 10.6.6 (10J3210)
•Later OS    Mac OS X 10.6.7 (10J4139)
{specs from http://mactracker.ca database}
Anyway, perhaps another volunteer contributor has
ideas that may work, so I have to go about other
obligations and have to go offline now.
PS: I just noticed your other post, and Recovery
could be helpful, but may rely on the Apple ID
of the previous owner if an older OS X 10.7 or
later was installed & still present in the MB/Pro.
Usually a purchased code was involved in a
new install of Lion, via the Mac App Store while
MacBook, etc was running in SL OS X10.6.8...
Good luck & happy computing!
edited