Work being done to it will show up as heat, which indeed is subject to e=mc^2. But when it cools there's no residual mass. The data doesn't actually have weig

Work being done to it will show up as heat, which indeed is subject to e=mc^2. But when it cools there's no residual mass. The data doesn't actually have weight because they aren't going to store a 1 or a 0, but rather do something like store 01 vs 10.