You may want to look into something called the X-Clamp Method, it required replacing the X-Clamps, which are brackets that hold the CPU and GPU heatsinks in place, These will warp over time, to the point where they put uneven preassure on the CPU or GPU causing it to form a cold joint (Where the chip is not fully connected to the motherboard causing it to malfunction) This causes the red ring of death. If you are comfortable doing this, it required replacing the clamps with screws, and opening the Xbox. You can buy kits that include the screws and washers, and maybe the thermal compound (Which also needs re-applyment)