Reseting GPU settings

[Kasenumi]

Hi everyone
How can I reset my GPU settings to default? My friend who is "experienced" with PCs was helping me for years with my PC and while cleaning the dust and changing the CPU thermal paste did something to my GPU (in BIOS or smth), either undervolting or setting it to a different power mode (so I can pay less for electricity as he told), I don't quite know what exactly he did or how to fix it, he can't explain what happened either. 
The image on the screen started lacking colors and contrast was behaving a bit "funny, opening Start Menu caused contrast and brightness animations on desktop.". Reinstalling Windows didnt help. Somehow I managed to stop this from happening, I have no idea how, tried everything, millions of guides on internet. It just stopped. Tried reinstalling GPU drivers, OS reinstall, something must have helped. 

Though I am not exactly sure if I really fixed it and if I have all that millions of colors displayed correctly. Sometimes it seems like image lacks colors or they aren't as smooth.
Is there a way to reset GPU to the default settings to make sure everything is OK?
 

[Hairless Monkey Boy]

And you are sure it isn't the monitor that is the problem? Or the display cable?

[RONOTHAN##]

Unless he did something real crazy like reflash the vBIOS, a Windows reinstall should've fixed it. It's very possible that the cable, the monitor, or that specific port on the GPU just happened to die at the same time. I'd try new versions of all three of those if possible. If none of those work, try the GPU in another system to see if it still has issues, which would mean that the GPU just happened to die at the same time you tried undervolting or whatever. 

[Whiro]

21 minutes ago, Kasenumi said:

Hi everyone
How can I reset my GPU settings to default? My friend who is "experienced" with PCs was helping me for years with my PC and while cleaning the dust and changing the CPU thermal paste did something to my GPU (in BIOS or smth), either undervolting or setting it to a different power mode (so I can pay less for electricity as he told), I don't quite know what exactly he did or how to fix it, he can't explain what happened either. 
The image on the screen started lacking colors and contrast was behaving a bit "funny, opening Start Menu caused contrast and brightness animations on desktop.". Reinstalling Windows didnt help. Somehow I managed to stop this from happening, I have no idea how, tried everything, millions of guides on internet. It just stopped. Tried reinstalling GPU drivers, OS reinstall, something must have helped. 

Though I am not exactly sure if I really fixed it and if I have all that millions of colors displayed correctly. Sometimes it seems like image lacks colors or they aren't as smooth.
Is there a way to reset GPU to the default settings to make sure everything is OK?
 

Reset the bios to the default settings, if he played with undervolting in bios this should help.

You can reset the UEFI settings (clear CMOS) by one of the following methods:

 1. Go to the Exit tab in the UEFI and select Load Optimized Defaults.

2. Press the Clear CMOS button on your motherboard (if it has one).

3. Unplug the computer and remove the coin cell battery on the motherboard for a few minutes and then reinsert it.