gameplay issues on new pc

hi all im new to these forums so please be patient with me. i recently purchase a new pc to play star wars call of duty and battlefield 1 etc but im having major problems playing these games constantly getting poor game play like stuttering, lag etc only on multi-player . i checked task manager and my cpu runs at nearly 99% and my ram the same now i spent just over a £1000 on this system so i expected it to play these games but i cant even on low settings and ive tried everything to fix these issues but no joy so if someone has had same issues with same set up ive got i would appreciate some good advice. my specs are:

lenovo sytem

nvidia gtx 1070 graphics card 8 gig of ram

8 gig x ddr5 ram

1tb hard drive 

250 ssd drive

i5 6400 processor intel