Thx all for answers and tips. But Server hardware is totaly fine, I'm use hetzner dedicated server EX40-SSD. And also I'm host one more minecraft server, on same machine, couse processor have 8 cores, the same forge, mach more mods about 140, but GT 5 not included in that pack, and I'm don't see the same problems(periodic lags by loading/unloading chunks), on it. How I'm can check my hardware on overheating or defects? I'm use debian 7 on my server.
Can I'm know the GT is include the chunckloading by it self?
Also thx for tip about second drive for OS, appreciate it.