configuration - High load, low cpu utilisation - system crashing periodically - Ask Ubuntu

i have installed fresh version of ubuntu 16.04. system falls on regularly message below in syslog.

info: rcu_sched detected stalls on cpus/tasks:      2-...: (1 gps behind) idle=363/1/0 softirq=167130/167130 fqs=7845837      (detected 0, t=7845872 jiffies, g=197552, c=197551, q=225464) 

uptime shows following load:

 09:10:42 22:36,  1 user,  load average: 4.04, 4.02, 4.00 

top shows similar despite high idle usage

top - 09:11:17 22:37,  1 user,  load average: 4.12, 4.05, 4.01 tasks: 214 total,   2 running, 212 sleeping,   0 stopped,   0 zombie %cpu0  :  0.0 us,  0.0 sy,  0.0 ni, 97.3 id,  2.7 wa,  0.0 hi,  0.0 si,  0.0 st %cpu1  :  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st %cpu2  :  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st %cpu3  :  0.0 us,  0.0 sy,  0.0 ni,100.0 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st kib mem :  8112956 total,  4986392 free,  1399292 used,  1727272 buff/cache kib swap:  8325628 total,  8325628 free,        0 used.  6313608 avail mem 

free information shows plenty of ram available.

total        used        free      shared  buff/cache   available mem:           7922        1366        4865          35        1690        6161 swap:          8130           0        8130 

i don't see i/o issues iotop:

total disk read :       0.00 b/s | total disk write :       0.00 b/s actual disk read:       0.00 b/s | actual disk write:       0.00 b/s 

the consistency seems cpu2 causes stalls. else should looking @ determine reason crashes?

it seems caused missing graphics card driver. in case nvidia. installed these drivers , disabled uefi safe boot , have been crash free on day.