If statement vs if-else statement, which is faster?

I argued with a friend the other day about those two snippets. Which is faster and why ?

value = 5;
if (condition) {
    value = 6;
}

and:

if (condition) {
    value = 6;
} else {
    value = 5;
}

What if value is a matrix ?

Note: I know that value = condition ? 6 : 5; exists and I expect it to be faster, but it wasn't an option.