My Y580 does a ticking/popping sound when it heats up during gaming at around 70C. The sound comes from the exact spot every time, which is pretty much under/around the touch pad. Any idea what that is?

It's hard drive. Y580 has a very unfortunate placing of the hard drive, which causes it to overheat. HDD overheating is dangerous when it's like that for extended period of time. The standard hard drive in y580 has an operating temperature of up to 55°C. Everything above it will shorted drives' life. You can check its temperature using many apps e.g. CrystalDiskInfo. There are two ways to make sure it won't overheat. The first is to remove the bottom cover and use an active cooling pad. When it comes to HDD temperature it is very effective. Don't expect much regarding CPU and GPU temps though. The other is to replace the HDD with SSD, and put the HDD in a caddy instead of optical drive.

It does seem to be the HDD.. That popping sound also occurs right when I turn on the laptop which I guess is normal. When the laptop heated up, the sound was heard several times continuously... Any idea what the sound is exactly?

It's probably gases inside the HDD are expanding due to heat applied. If the volume of the HDD is fixed, pressure inside the HDD is increased when the temperature of the gas is increased. Since there's more pressure inside the HDD, it causes the head and platter to adjust to elevated pressures thus the popping sound. This is a really good article of that explains how HDD works: http://www.acsdata.com/how-a-hard-drive-works.htm

Hmm, makes sense but if we assume that the head and platter were adjusting to the new pressure, the temperature was constant tho, it was stuck at 55C.. It never went higher beyond 55 yet the popping sound happened more than usual.. I mean, I do hear it once when the laptop is turned on (since I bought it) and from time to time during operation, but last night it happened just A LOT.

Head repositioning by itself is not bad. If it does it constantly it migt be something called "click of death", when the drive repeadetly repositions the head and fails every time. I don't think you have anything to worry about (as of now). Just try to keep the HDD within it's operating temperatures and keep in mind, that all hard drives will fail one day-> make backups of important data!

i would install the trial of hd tune and give it a health check jsut to be sure your drive is not dying.

bumppppp