Right, looked at it and... you have dry joints for sure my friend. The card is bad unfortunately. Look at the block of six, the top left solder joint. See that telltale crack circling the pin? There's your dry joint right there. There are one or two other potential candidates, but I can't quite tell. And unfortunately, if you see one, there are guaranteed to be more. And they can be in places that you can't get to, either. This is a significant reason why electronics that run cool are so highly valued. Less heat stress, less cracked joints, it's a direct relationship. The brown icky-looking stuff is indeed dry solder flux and can be ignored. It looks like your friend sold you a faulty card. I wouldn't rule it out that it played up intermittently for him and he just didn't tell you.