A few weeks ago, a friend updated their computer with a newer GPU (Graphics Processing Unit), and they gave me their old one so I could work on building my own computer. I had some other parts, but long story short my new computer didn't work, and I put the GPU back into it's packaging. 

My current PC isn't built for gaming, and so it's unable to play a couple games that my friends and I like. I've been using my brother's computer, but before he let me use it I've always made sure I had his permission. I've let him know what games I have downloaded, and I've not done anything to it without his OK.

Recently, he's been trying to build another computer to act as a server. When I was working on my failed computer project, I told him he could use my current GPU, because I would be using my newer one. Servers dont really do anything graphics heavy, so an older GPU would work fine for building it. Of course my PC project fell through, so I still have to use my older graphics card in my current PC.

Cut to today, and I'm using his computer. I notice on his desk a few pieces to the packaging for my newer GPU, so I take a look around. I notice that he has installed my new card into the server PC he's building. He didn't ask my permission, he didn't even tell me about this. I would have been fine with him using my card, but he didn't even let me know he was using it. After I removed it from the server PC I texted him and told him that he could "get his own fucking graphics card," and he told me to get off of his computer. 

TL;DR: My brother took my graphics card and used it for a computer he was building. I wasnt currently using the card and would have let him use it if he asked, because he lets me use his gaming PC. He didn't ask to use it though, so I took it out and said some rude things over text. He seems to have responded by not letting me use his computer anymore. 

AITA?