Sounds like your PS3 is at least 4 years old.

If your PS3 has gotten louder than when you first bought it from the store (I assume you are the 1st owner), then you should probably change your thermal paste.  Vacuume and clean it out while your at it.  ARCTIC SILVER 5 is good to use.

And like you were told, when having long gaming sessions, don't just turn it off...allow it to idle for 5 or 10 minutes so it can cool down.

It is three years old (yesterday was its birthday :) ). It was louder in summer ( it was very hot here) but it is normal now. I don't know much about changing thermal paste but I'll give it a look. 

Thanks for the answers.

Oh...well, happy birthday.  :P

If you don't mind me asking.....How much did you pay for your 40 gig fat 3 years ago when you bought it?

Thanks :). A lot of money, I will be a little embarrassed to say it :P. It was around 500 dollars with Motorstorm and a HDMI cable.

Leave it on for a little while after playing, and honestly don't worry about the fans going on for a 1-2 minutes orso after you shut it down, even the Xbox 360S console does this at times for because it's either still busy, or wants to cool down just a little bit.

$500?  For a 40Gig?  That was a pretty terrible deal.

Mine is an 80Gig, came with Stranglehold and a verticle stand for $400 a few days after Christmas 2008 at FRYS ELECTRONICS (actually I paid $415, and went back to get the $15 difference at New Years, which I used to get a Motorola Bluetooth that was on sale for $30)

Anyways, In September 2011, there was a hot "end of Summer" day, and my PS3 turned itself off. So I opened it and went to Fry's and got the Actic Silver 5, and I changed it.

My PS3 wasn't  loud, per se,  but I could tell it was a slight bit louder than when I originally brought it home.  Now, it runs just like the 1st day.

I suggest you do this now, because even though I could have waited another 6 months to a year or so (the old paste wasn't completely dry yet), this is something you want to get the jump on early......DO NOT PROCRASTINATE.

You probably have a 65nm Cell CPU just like mine, which doesn't run as hot as the original 90nm versions, you should do this this week....go to Amazon and get it, and use the YOU TUBE tutorials....it's not really hard. 

If you need a talk through pep talk, you can hit me on PSN....same name.

Good luck.

Actually that was very good in my country LOL. It was at that price without a game and a cable normally. I had a friend from USA come over and after seeing the prices of electronics he was like Jackie Chan's mind-blown picture. 

 I'll do it in a few days for sure. The problem may be or may not be related to thermal paste but it is probably dried anyway.

I had that problem just after I got my PS3 back from repair, about a year and a half ago. The fans would keep running on standby mode (though obviously not when it was off at the back).

I'm not sure why this worked, but it did: I took out the hard disk, wiped it with a tissue, and put it back in. The problem has never reoccurred.