PLEASE HELP! (Margin Account Question)

I have a question about trading securities in a margin account and if
anyone has any advantageous information I'd greatly appreciate it.
I've only traded in a cash account and I'm thinking of applying to
open a margin account in order to be able to day trade. The thing is
though in order to minimize risk at first I don't want borrow at all.
So my question is, can someone open a margin account and still buy
securities without using any of the available margin buying power they
have? If I open a margin account with $5,000 and want to buy
securities, can I use only that $5,000 and not borrow anything or would
I be required to borrow $5,000 and execute the buy with $10,000. I'm
curious because of the obvious risk involved with buying on margin.
There is a greater reward of course but also a greater risk, therefore
I want day trade for a month or two but I don't want to buy on
margin, so I'd like to know if it is possible to have a margin
account and buy without using the margin buying power available to you?
I'd greatly appreciate any advice. Thank you.