HDD write speed decreased

Aug 13, 2018
23
0
10
After i completely wiped out my HDD, i benchmarked it with CrystalDiskMark and got 60mb/s write and 60mb/s read, but after i copied a 34gb file into the HDD, i re-ran the benchmark and i got only 15mb/s write (while read speeds stayed the same), i also ran the benchmark multiple times
 
Aug 13, 2018
23
0
10


Hitachi is very very old, (1034 days run time) and it's also the OS disk, it works very well for me (besides long boot time)
You said the Seagate looks normal, but why do i get 15mb/s write on it on different benchmarks ?