Question Why do I get low fps with low usage

[FlagrantSky]

Right so when I play some higher graphic games my fps plummet if I’m in a car or something as obviously I’m going faster however my gpu and cpu usage both stay quite low
also if I decide to upgrade what should I upgrade first
specs:

gpu: msi 1070 8GB slightly overclocked
CPU: intel core i7 10700F overclocked to 3.6GHZ
Ram: 2X8GB ddr4-3200
Motherboard: MSI B460M PRO-VDH

 

[rgd1101]

what the ssd? how full it is?
brand and model of the psu?

 

[FlagrantSky]

Can’t remember my ssd but it has at least 500GB left and my psu is 750w can’t remember the brand or model unless you need it then I can find out

 

[FlagrantSky]

what the ssd? how full it is?
brand and model of the psu?

Cooler Master MWE 750 Bronze 230V V2 - UK Power Supply Unit, 80 PLUS Bronze, Temperature-Responsive HDB Fan, DC-to-DC + LLC Circuit with Single +12V Rail - 5 Year Warranty https://www.amazon.co.uk/dp/B08D9L9XNN/ref=cm_sw_r_cp_api_glc_i_QJX1SD1MJA3KGCXVJJND
That is the link