I'm surprised you could find "raw" nibs. I thought nibs were the roasted, de-husked cocoa beans.
If they are really raw, I would roast them. Doubt you'll get much "cocoa flavor" from raw nibs. I know a guy who makes chocolate. I asked him about the temps he roasted cocoa beans at, and though he was a little tight lipped about the specifics, he said this:
"Proprietary... Jk... Well kinda... Let's just say, 300F is too high and, well, I haven't found the lower limit yet, though I'm guessing it's around 215F. But I would recommend messing around with about 260F or so for now."
I'd probably roast them on a cookie sheet in the oven.