I just ran the csgo FPS Benchmark and i noticed that my cpu was at 80 - 100% the whole run and my gpu was sitting at 30% and at some demanding areas me gpu went up to 100% and then went back down to 30% again.
Single channel or dual channel makes no difference to Intel unless you saturate the bandwidth, which is doubtful. And even if somehow you do manage to saturate single channel bandwidth, dual channel only offers upto @ 20% ram performance difference.
That's an i7. CSGO only uses 2 threads, so there's no way you'll be seeing anywhere close to 100% usage on the full cpu, only possibly on a per core basis.
My guess would be a Trojan or possibly malware is swamping the cpu whenever you get online. Something is using a big chunk of resources to be using up 6 other threads, if it was an i5, that'd be more understandable in BF5, as that'll use upto 8 threads without issue, swamping the 4 threads available. But not CSGO.