This article is for the reader who is already familiar with the basics of Xbox overheating. You have already tried using your machine in cool, well-ventilated places away from other sources of heat, limit the hours of use, keep the vents free of dust and obstructions, and keep the electrical block free of rugs. I will discuss how a bad connection between the CPU and its heat sink or the GPU and its heat sink can cause drastic overheating issues.
At its best, the Xbox has a cooling system that barely keeps up with normal heat buildup. Because it has little cooling capacity to spare, it doesn’t take abuse well. Most people would reasonably expect an Xbox, however abused, to take at least a few minutes to overheat.
So if your Xbox is getting the 2 red lights error (indicating overheating) within a few seconds of turning it on after a cold boot, you might be wondering how this could be possible.
One of the reasons for overheating so quickly is that the CPU or GPU has shed their heat sinks. A heat sink is a device that extracts excess heat. To do its job properly, the heatsink must be in good thermal contact with the CPU (or GPU, as the case may be).
A CPU or GPU can heat up extremely quickly if not cooled down at all. Both units consume a lot of energy for their size. It would only take a few seconds for this electrical energy to overheat an uncooled GPU or CPU. This overheating is so fast that the rest of the console wouldn’t even have time to heat up when the overheated CPU or GPU causes the Xbox to shut down. So you end up with a console that still feels great but shows the two red lights error.
There are several ways the heat sink can lose thermal contact. Either the thermal paste is extremely old, or too much thermal paste was applied initially, or there is no paste at all. Perhaps the wrong (too thick) washers were used during the assembly process, or the heat sinks were not screwed in properly, or perhaps Microsoft left some foil on the heat sink.
When you replace the thermal paste, please remember to clean the old paste first. An alcohol wipe should work for this. Avoid applying too much thermal paste as only a thin film is needed to ensure there are no air pockets between the heatsink and the CPU (or GPU). A good paste to use is Arctic Silver. Keep track of the spacer washers you remove as they must be replaced during assembly.
If you have never tried this before but are determined to do it yourself, it is highly recommended that you get a guide for this type of repair. Also note that your warranty is void once you open the console. Good luck.