Sounds like heat or PSU. Check to see if the HS is attached securely and the fans are operating. You likely only need a case fan. Check to see if you fan runs of the PSU, if not theres your problem. If you are on a tight budget, you can fix you power supply, but the warantee, if one exists, will be voided. Be sure to power down, unplug, and remove the PSU. Then unscrew the cover on the PSU (some screws may be beneath the label) and remove the fan. Measure the size of the fan and note the type of plug (if there is one). Then get a new fan of the same dimensions with the proper plug and install. If there is no plug you can cut, strip, and splice; using butt-connectors (radio shack) but you will need a crimping tool. This is also useful if you PSU is too loud, however make sure to get a fan that has enough air flow to accomodate the cooling needs of the PSU. Best Wishes, Mav.