My ps3 has ylod but still works

i have a cechl01 ps3 that i recently opened up to clean dust it has gotten ylod but still works after a few times of turning it off and on. it lets me do everything but after i get in a game for 1 minute or so, it turns off with ylod. i have cleaned the dust but never changed the thermal paste also, when it gets ylod i hear a click from the psu and also when i turn it on the fan ramps up