|"There is no cover on the case "|
This is part of the issue. Might just be able to install a muffin fan in that case or two.Case's, even plastic ones form a shield. Plastic ones are painted with a conductive paint to form a shield.
Best choice would be to use the on-off switch. Do you really need to have both on at the same time?
You would be better off also by moving the computer away would be my guess too. Might loose magnetic data if too close to an older set.
"Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10