How do I get rid of the loud noise

This is not a solution, but I hope it helps in finding one.

I bought the 80gb Metal Gear PS3 with software backwards compatibility.

I have attempted to correct this noise problem by stripping down the PS3 and replacing the thermal paste and cleaning the unit thoroughly with an air can. It did not correct the problem. I am unsure if the unit is actually overheating or if the temperature sensor is reading higher-than-actual temps. The air at the exiting back of the unit feels warm, but not hot like my twin NVIDIA 275GTX SLI PC. I'm not sure if comparing the two is an accurate measurement of what would be deemed normal exhaust temperatures or not, but the 275s are much quieter than the PS3 even when I manually crank up the fans to about 80% to keep them running cool.

Lastly, FYI Sony's will allow you to submit your unit for repair at no cost if it is under warranty, and $150 if it's not (at the time of this post). A Sony refub does have a service warranty, so if your replacement is recent gustavo, they should provide you with another unit again if you are willing to go without your unit for a few weeks again.

Just so you know, Sony will not accept refurbish units for repair. They will send your unit back to you if it was not refurbed by them or an authorized dealer.

My 60 gig had YLOD and Sony sent it back because GameStop refurbed it first.

I'm having a similar issue with my 80gig now. I got replacement ps3 slims so my 40g, 60g and 80g are just collecting dust.