Magical computers just can't work. Not because "It is technology, therefore it cannot work around a Wizard" but because of the magnetics. I've honestly thought about telling you you would need to Macguyver a motherboard and make computer components that run on magic and you would need to be a sensitive, but in the end it comes down to Magnetics. The Hardware of a PC can be duplicated, but the software cannot be. Wizards wipe magnetic storage devices and therefore could not be in the vicinity of a normal hard drive let alone tiny magnetic devices such as Processors with BIOS on them. Without the ability to store and access information, a computer cannot work. Therefore, no magic computers.

Although if I were a wizard I would just get a really long extension cord and go through a lot of mice and keyboards if not make a keyboard out of a typewriter and Macguyver a Trackball.

Put the CPU in a Faraday cage, as well as the magic circle. A 60's vintage dumb terminal just might hold up better than a modern mouse and keyboard. Our hypothetical technomancer would have to be Unix geek. (Makes sense...)