In my testing, I stress test for 12 minutes, then I play Fallout NV just fine-1024x768 High Settings 0xAA, 2xAF; 24 average FPS unmodded, 18 FPS with graphics mods, no abnormal stutters and fps drops, no artifacts, no BSODs, no crashes.
Then after 2 hours I restart to check BIOS temps, NB at 69º and touched the heat sink for a full minute and it was only as warm as my armpit.
May you assist me in determining and confirming the natures of the 38ºC reading and the outrageous 68ºC BIOS reading, my lords. Thank you.
Millions of TH members, thousands of readers and probably a few hundred ECS-A890GXM-A V1 users, and I answered my own questions. Thanks for the silent motivation everyone.
To all current users or about to use the same Mobo esp noobs like me, you may encounter this issue and there's no need to worry.
I simply decided to buy a a gpu and after installation with the latest 11.2 drivers, I checked BIOS and it gave me the new "true" NB temperature of 41°C, which corresponds to all temp monitor readings shown in my previous post.
It was 68 deg, down to 41°C and all it took was a Sapphire 5570 1 GB Version 3 (new cooler similar to HIS). This card is amazing, OC'ed it to autotune 950/1435 respectively using CCC. 100/135 clock gains, post mortem cool and silent as Sam Fisher. I'll let you know about the elec bill increase a month from now.
Now I know why the heatsink was as warm as my armpit, cause it works! ECS- bad customer service, very durable mobos-my 3rd in 7 years, the other 2 still perfectly functional. Hope this helps similar issues current and future.