Download mode on windows?

So if I want to download a big file or game thats 10+ Gigabytes,  and then I decide to call it a night but the download is not finished.  Is there a way of leaving your computer on for the night to download the game, but also setting up your computer to use as little resources as possible in an effort to reduce temps and to extend the life of my machine just a little bit because who wants a dead computer?  

Is there a third party software that can do this?

Is this already an automatic feature and i don't know?

Is there something I have to do in the bios?  

Thanks for your input!

Leave ur computer on?

Either use a timer that shuts down the computer at whatever time, there are quite a few of those.  Or if its a file you're downloading through the browser, I use jDownloader (its a fgree java-based download manager) and it allows you to automatically shut down the computer when the downloads have completed.