Strange very HIGH CPU usage

Dear Experts please help me on this strange behaviour, in the last three days, my server have a pike of CPU usage, 7 to 10 times per day, it reaches 10 and then few minutes down back to less then 1%, but i dont really find what is the cause, hereafter top during the pike : Linux 2.6.32-279.22.1.el6.x86_64 12/23/2013 _x86_64_ (4 CPU) Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sda 46.51 603.66 819.51 10964390258 14884888256 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sda 83.00 24.00 2288.00 24 2288 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sda 13.00 0.00 304.00 0 304 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sda 0.00 0.00 0.00 0 0 Device: tps Blk_read/s Blk_wrtn/s Blk_read Blk_wrtn sda 36.00 1568.00 0.00 1568 0 Linux 2.6.32-279.22.1.el6.x86_64 12/23/2013 _x86_64_ (4 CPU) Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sda 8.14 80.05 23.91 22.61 603.66 819.51 30.60 0.00 0.09 5.08 23.64 Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sda 0.00 72.00 12.00 27.00 720.00 800.00 38.97 0.88 22.23 6.69 26.10 Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sda 0.00 6.00 10.00 23.00 704.00 224.00 28.12 0.20 6.67 2.09 6.90 Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sda 0.00 2.00 16.00 3.00 136.00 40.00 9.26 0.10 5.26 3.16 6.00 Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s avgrq-sz avgqu-sz await svctm %util sda 0.00 30.00 27.00 4.00 256.00 272.00 17.03 0.25 8.19 3.29 10.20 Linux 2.6.32-279.22.1.el6.x86_64 12/23/2013 _x86_64_ (4 CPU) 03:14:31 PM CPU %usr %nice %sys %iowait %irq %soft %steal %guest %idle 03:14:31 PM all 9.32 0.11 3.85 6.48 0.00 0.57 0.00 0.00 79.67 03:14:31 PM 0 13.45 0.14 4.54 13.18 0.00 2.26 0.00 0.00 66.42 03:14:31 PM 1 7.72 0.05 3.54 5.18 0.00 0.00 0.00 0.00 83.50 03:14:31 PM 2 7.85 0.20 2.67 5.42 0.00 0.03 0.00 0.00 83.84 03:14:31 PM 3 8.24 0.05 4.63 2.15 0.00 0.00 0.00 0.00 84.93 top - 15:14:31 up 210 days, 5:19, 0 users, load average: 10.18, 3.47, 2.01 Tasks: 270 total, 1 running, 268 sleeping, 0 stopped, 1 zombie Cpu(s): 9.3%us, 3.8%sy, 0.1%ni, 79.7%id, 6.5%wa, 0.0%hi, 0.6%si, 0.0%st Mem: 7801336k total, 6497516k used, 1303820k free, 734008k buffers Swap: 10239992k total, 27472k used, 10212520k free, 3457144k cached PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 20243 root 20 0 15164 1212 808 R 2.0 0.0 0:00.01 top 1 root 20 0 19352 640 408 S 0.0 0.0 1:58.49 init 2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd 3 root RT 0 0 0 0 S 0.0 0.0 15:39.56 migration/0 4 root 20 0 0 0 0 S 0.0 0.0 6:24.75 ksoftirqd/0 5 root RT 0 0 0 0 S 0.0 0.0 0:00.00 migration/0 6 root RT 0 0 0 0 S 0.0 0.0 0:34.24 watchdog/0 7 root RT 0 0 0 0 S 0.0 0.0 8:45.61 migration/1 8 root RT 0 0 0 0 S 0.0 0.0 0:00.00 migration/1 9 root 20 0 0 0 0 S 0.0 0.0 7:28.24 ksoftirqd/1 10 root RT 0 0 0 0 S 0.0 0.0 0:11.89 watchdog/1 11 root RT 0 0 0 0 S 0.0 0.0 9:06.23 migration/2 APACHE STATUS Current Time: Monday, 23-Dec-2013 15:14:23 CET Restart Time: Friday, 08-Nov-2013 11:44:41 CET Parent Server Generation: 328 Server uptime: 45 days 3 hours 29 minutes 42 seconds Total accesses: 36478399 - Total Traffic: 1334.5 GB CPU Usage: u8.37 s5.1 cu127.95 cs0 - .00363% CPU load 9.35 requests/sec - 358.7 kB/second - 38.4 kB/request 74 requests currently being processed, 0 idle workers WKCWRWKKKWKWWWKKWKKKCKWKKKKKWKKKKKKKKKWKKKWKKKRRKKKKCWKKKKKKKKKK KKRRRWWWWWSS.................................................... ................................................................ ................................................................ Do you find please the root cause of the spike ?