Max temp for your CPU is 95°C and whilst you're getting hot there those temps are OK. I'm puzzled that the CPU temperature rises when the screensaver kicks in? That sounds as though some background process might be starting when the system is idle. Anyway, this doesn't seem to be temperature related - at least not CPU temperature related.
Whatever this is it certainly doesn't look like a software or driver problem. All of the reboots in the log happen suddenly, there seems to have been no opportunity for Windows error recovery to become involved (there are no BSODs for example) and that looks very much as though some hardware is failing underneath Windows. There are a couple of things we can try though...
1. Windows will auto-restart if a 'system failure' occurs and you can stop it doing this. That might just let you see any error messages perhaps. In the Run command box enter the command sysdm.cpl and click OK. The System Properties dialog will open. Click the Advanced tab and then the bottom Settings button (in Start-up and Recovery). Ensure that your dialog looks like this...
It's important that the 'Automatically restart' box is NOT checked.
2. The other thing you can try is to
start Windows in Safe Mode (without networking). In Safe Mode a stripped-down version of Windows is loaded with only critical services and drivers loaded, typically no third-party drivers are loaded. This means that you won't be able to do any useful work in Safe Mode; many devices will not work properly (or at all) because their drivers have not been loaded. Your display will be very low resolution for example, because you'll be using the basic Windows display driver. The point of Safe Mode is to see whether it fails, so do try and use it as much as you're able (which won't be very much), also leave it to sit idle in Safe Mode for a while (make sure it doesn't sleep, hibernate or shutdown). If it fails in Safe Mode then it's prety definitely a hardware problem, but if it doesn't fail then we have a fighting chance of finding out what's causing it.
