Pc loses fps?

I have a question about my pc I really don't know my way around it is a rtx 570 graphics card and an amd a10 7870k built in with 11 gb ram I know that it is not a good pc but it should be enough to play on medium settings i play gta on the pc which works very well fortnite too but i have a little problem and when i remove my side cover i have 120 fps with stuttering to 60 50 fps again and again when i leave it on then i have 70 fps with stuttering at 50 fps in tournaments I hardly have more than 40 fps someone knows what that could be

Check the temperatures of your PC.

The temperature is 50 degrees + - 10 degrees

If better ventilation solves your problem, you obviously have a build-up of heat somewhere. So go ahead and find out which component is slowing down due to thermals.

OK thanks

You have 3 problems:

1. Your CPU is a dual core with 4 threads (realistically speaking). In addition, it is extremely weak in the CPU performance (regardless of whether it has 4GHz or not if the IPC performance is not right). CPU annoying games in particular suffer.

2. 11GB DDR3 RAM is very unfavorable… Either 8GB in dual-channel (2 x 4GB) or 16GB in 4 x 4GB (or 2 x 8GB).

These are your main problems.

3. Your temperatures seem to be rather bad, check your airflow in the case.

Which? CPU? Graphic card?

OK thanks

Gtx 570 and amd a10 7870k

Do they both have exactly the same temperature while playing or what?

Yes similar