Game just started lagging.. only uses around 20% of ram and processor according to task manager

Beamng ran great for about a month. All the sudden it just started lagging out of nowhere. I dont have any viruses, and it makes the game lag so bad its almost unplayable. I Turned the settings down from about medium to the lowest they can go with no difference. According to my task manager the game isnt using any ram or processor power when it lags like this. The computer works fine and just as fast as normal whereas the game lags like crazy. Any Suggestions? Answers would be greatly appreciated and thank you in advance

 

That is fairly weird.
How old is your system? It may be failing ie your GPU might be dead etc.

 

Also check cooling. Might have been clogged with dust.

 

My system is about a year old, and always ran everything fine. For example, it ran RoR flawlessly on high settings and only lagged on Skyrim on ultra settings.. My GPU is fairly cheap though i never got around to getting a really nice one, so you could definitely be correct. Thank you

- - - Updated - - -

No dust, but thank you for the suggestion

 

A gpu usually doesn't degrade like that though. Generally, you will see corruption or display driver crashes due to degradation.

I think temps still might be the right direction, what does gpu-z report? Also, make sure the CPU isn't throttling due to c-state/power efficiency limitations or temps.

 

What about other games. Do they also lag when previously they were not?

 

No:/ just beamng.. which is my absolute favorite game right now so it really sucks haha

- - - Updated - - -

Please translate so i can understand this.. lol. Sorry, I did build my own computer but im still not too familiar with terms like those... Thank you
edit: Terms as in Gpu-z and 'CPU isn't throttling due to c-state/power efficiency limitations or temps'