I'm not sure it's the right place to ask that but... it mainly concerns a game sold on GoG.
My graphic card is a GeForcre GTX 460 and I climb to up 75° when playing some games such as King bounty, there's no artefacts or anything else but I fear the card will not last long if this continue, do you think it's a bearable temp ?

It's a prefectly normal temperature especially if you are playing King's Bounty because the game has some reported issuses that heat up your gpu.
Before I cleaned my laptop and put a new thermal compound my gpu (Geforce 7900gt) would spike at 105° celsius while playing Kings Bounty.
Now it's between 65-75°.

The 240m in my Asus laptop sits @ 100°c+ no matter what game I play.

Not sure what to think about that.... mine is actually a new build and well ventilated tower (built 1 month ago) and the game seems to even climb up to 80...

75 is perfectly fine for the card. nothing to worry about

70+ is completely normal for the 4xx series as others have said, so out of interest have you suffered any of the boot up problems being reported with the 460's?

Nope, the only thing worth mentioning was the card "whistling" in the early days.

75 is nothing to worry about. I wouldn't be concerned unless you're getting to 90+, and even in those cases cards will typically shut down or start showing artifacts before any damage to the hardware is done. Something to also consider is that many cards by default set the fan speed fairly low (as in, say, 50% of the max speed), which naturally results in higher temperatures. There are a variety of third-party tools available to better control the fan speed (either locking it in to a higher speed, or setting variable speeds based on card temperature), so this can be used to help keep card temperatures down if you're still worried about it.

If temps are a great concern to you, as they are to me, make sure you download Rivatuner or a similar alternative to set up your fan speed accordingly. As far as I can remember, I always had to tweak the fan speeds manually, otherwise they'd never run at the desired speeds.

Thanks I got one program to handle this, my fans where actually running at 40%, duh.... and the dynamic fan control speed doesn't seem to be working fine.
Alas, up to date (I think) Rivatuner doesn't seem to work with recent NVIDA drivers.