Thank you for your kind answer.
Actually hard drive corruption happenned to me once (thankfully I noticed it early) so now I am very cautious about hdd temperature besides my computer six years old. The Smart data from HD Tune looks fine but I don't know I cleaned the inside of the case, cpu, gpu fans. There is a fair space between HDD and SSD etc. But the case is very small, cables are so messy, maybe it's because of that. But this new idle temperature is that earlier temp. during the computer was fully loaded. Hope nothing is wrong, thanks again.
HD Tune: WDC WD5000AAKS-00V1A0 Health
ID Current Worst ThresholdData Status
(01) Raw Read Error Rate 200 200 51 0 Ok
(03) Spin Up Time 140 138 21 3991 Ok
(04) Start/Stop Count 99 99 0 1903 Ok
(05) Reallocated Sector Count 200 200 140 0 Ok
(07) Seek Error Rate 100 253 0 0 Ok
(09) Power On Hours Count 90 90 0 7884 Ok
(0A) Spin Retry Count 100 100 0 0 Ok
(0B) Calibration Retry Count 100 100 0 0 Ok
(0C) Power Cycle Count 99 99 0 1891 Ok
(C0) Power Off Retract Count 200 200 0 128 Ok
(C1) Load Cycle Count 200 200 0 1774 Ok
(C2) Temperature 104 96 0 39 Ok
(C4) Reallocated Event Count 200 200 0 0 Ok
(C5) Current Pending Sector 200 200 0 0 Ok
(C6) Offline Uncorrectable 200 200 0 0 Ok
(C7) Ultra DMA CRC Error Count 200 200 0 1 Ok
(C8) Write Error Rate 200 200 0 0 Ok
Power On Time : 7884
Health Status : Ok