Q - What exact MOBO? Q - What BIOS version? Q - What exact Kit or Kits or RAM? ; Provide a link. Keep in mind the Rated Frequency/CAS Timings are for (1) kit not Kits or individual sticks placed together Q - What DIMM Slots is the RAM installed?
Now if the only problem is YouTube then try Disabling Hardware Acceleration ; many Browsers it's a known issue.
I had the same problem, it was tested from newegg RMA and it was a bad stick of RAM.