If you still have access to you brothers computer, then try the memory in there if his board will take it, oor even try your brothers memory in yours see how it fars, if not i can not offer any other suggestions than the mobo, but usually when a mobo goes you get a burning plastic smell and maybe even a little puff of smoke, but it will still power on, okey dokey sorry i could not help you anymore than that please let me know how you get oon with it.
all the best regards
Simshi