While playing the Sims 4, my PC will suddenly shut off.

How hot does your computer get ?

I tried to install Nvidia but it wouldn't work. I have a Lenovo Thinkpad edge. I'm not sure if it has a graphics card or not...

Ah it's okay. Luckily I have AMD control panel. I enabled vysnc and I hope it works, 

How do you enable Vnysc??? 

@meganrose1066 There are several ways to enable vsync and it depends on the video chip in your computer. There are 3 major video chips in use today - Intel, Nvidia and AMD (ATI). Vsync options is usually in the device driver and could be on the same page as the resolution.

when playing the game my monitor box thingy that i put the dvd in goes loader and loader and then my computer screens go black and it says the monitors going to sleep so when i use my mouse or turn the button on the computer to turn it on it will say no signal so i have to press the monitor button to switch the computer on. Also is it normal while you computer turns on for it to say all the coding on a black screen with white writing. im not sure if that could be why. i have a windows 10 and my dad bought it for almost £40 i dont like it when he waists money on trash. so if there is any way because i have tried them all it will meen a lot to me. Also we have the security thing bitfender and spy bot and a bitefender message would come up saying you can only have 1 security programme other wise your computer will crash but we got ride of spy bot and it still crashes even when i dont play the sims 4.

also my computer dosent heat up it only lasts 3 minutes.

This is what I do and it works start your computer offline then play I dont have that problem anymore and of course once a week go online for updates 

I have yet to test this but I think it could be right, I have also experienced this with Rebel Galaxy (really bad with that game as it corrupts the save forcing you to restart)

I have been dropping a few times since the recent Origin update, ie a couple of days ago no problems whatsoever, Origin updated and crashes. My motherboard is actually detects it as a power surge and shuts things off to protect the PC.

This happened on a prior Origin version as well. That time I took to testing heat which wasn't getting that hot (I got hotter doing other things) but cleaned my fans on GPU, Case, CPU and by the time I done that a new Origin patch was out and I did not have problems until now. I have just got done doing it again and since theres very little dust on those components I took my PSU apart and cleaned that too as it was the only area that had dust of any significant volume.

About to try Sims4 to see if that had any real effect.

Now going offline mode may work, but a better solution if you want online play might be to re-install Origin. I had to do this a month ago to get the FIFA18 demo to work, which screams to me that the Origin updater is not working as intended.

Edit: not really sure how so little dust changed much but it seems to have helped. just played 1.5 hours without a crash. You may want to check your graphics card settings (outside of game ie nvidia control panel) and turn on vsync. I did set it to "adaptive" judt dont go overboard on AA etc there as I tested these all maxed and it got my GPU working overtime, significantly slowing the game and making noise.

This is happening to me randomly also. I have tried all posted solutions. I even replaced my power supply and it isn't heat as I have been monitoring with cpu id. It is the only game that shuts off my computer and it happens randomly. It just shut off again after playing almost 3 hours (sometimes it only takes 15min). This is one reason I stopped playing this game.