For the last month or so I'm plagued with often, yet unexplainable spikes to 100% CPU load. Usually then Task Manager shows one or two processes taking 50%+ of CPU (not always the same: svchost, bitdefender/avira, task manager, explorer.exe, chrome, WMP etc.)
I reinstalled Win, switched from avira to bitdefender (avira slows with newest .NET installed, so thought maybe that), did a clean install (suspected malware, virus), got rid of flash (as even web browsing was bad experience), even youtube could become choppy - but no change. If left in idle, no spikes.
Replaced HDD in NOV'14 (previous one died in a crash accident - wife dropped laptop on the floor, causing hdd to detach, fall out and suddenly stop on the wall after several rollovers), so new one is 7200 RPM, 1TB 32MB cache HGST.
Weirdest part is that it started month ago or so. I know the system is old, and having NV160 on board means expiration date is already set, but I'm thinking graphics issue are somewhat Boolean in nature and with incubation in days on the outside, not months... So something else.
Anyone had similar experience? Or maybe some tips on concentrating efforts?
EDIT: More details on system. Win 7 Pro x64, 4GB RAM, T9400 2.54 GHz, Nvidia NV160 256MB.