The PS3 Yellow Light Of Death is a hardware failure of the PS 3. The cause is somewhat known, Some theories of the cause are: overheating (accelerated by dust build-up and or the PS3 being in tight quarters), blu-ray failure, a bad power supply, or a hard drive critical error.

Two Main Causes:

1. Hardware malfunction of the motherboard because of overheating (solder joints cracking and breaking) you can fix this by “reflowing”, by way of using a heat gun to re-melt the solder on the base of the chip to re-melt the solder.

2. The power supply has a bad capacitors or diodes. You can also fix this by “reflowing” however it’s harder to figure out due to the need to determine which problem it is.

Learn How To Reflow Your PS3 —> PS3 Repair Guide