If your box is malfunctioning due to simple overheating or poor heat transfer between the processor and heat sink, following instructions such as the X-clamp fix, or the instructable at
http://www.instructables.com/id/Fix-the-Red-Ring-of-Deathwithout-towels/ would be a good first place to start. As mentioned in that instructable, if your Xbox is covered under warranty, why on earth are you trying to fix it yourself? MICROSOFT WILL FIX IT FOR FREE IF SEAL IS INTACT AND REGISTERED TO YOU!!! Do NOT drill the case unless you want to buy a new metal shield (like I had to) to ship it off...more details in step 9. The steps in that and this instructable should only be undertaken on a machine that has no seal, is registered to someone else, and there is absolutely no way you can get Microsoft to do it for you under their warranty. If this doesn't fix it, we've got a bigger problem...