computer random lag spikes

i get some random lag spikes so often for about a month now these lag spikes happens in everything browsing, playing a video game , listening to music , videos , even when im browsing the pc folders , but this happens especially when im watching a video or maybe because it is easy to notice :\ ...... i have done everything i could to fix it i will be listing what i did here

1: changed windows to 8 and 8.1 and now im running win 7 and still got lag spikes
2: tried removing one of the RAM i got and work with only 1 to check the lag spikes and didnt work
3: removed 1 of the hard drives that i got and worked with 1 and didnt work
4: copied my files to a friend's hard drives and formatted all of my the hard drives and deleted volumes and reassigned it then recopied my files still didnt work
5: ran virus scan with kaspersky rescue disk and got some viruses but didnt fix the lag spikes as well
6: ran chkdisk and didnt find anything
7: changed the clock battery on the motherboard
8: downloaded new drivers and installed it nothing worked
9: cleaned the pc out of dust and checked all the fans didnt help as well

Edit : forgot to mention i live in egypt and we had here alot of power issues .. power keeps going off so often lately and computer keeps going off by force thats why i suspected a hardware problem but still cant detect the problem ... :(

PLEASE HELP ME :( :( :(