In my case, I tried non-ecc ram, full fan speed. Later I found out that airshroud, as previous pages mentioned, is the cause. When I swapped the ram sticks and bios batteries, I did not put on airshroud for convenience, thus the full speed fan noise. I think motherboard has some sensors for airshroud to automatically control fan speed. Anyway, in my case, airshroud is the issue. Luckily I did not buy another one from eisis, which does not have airshroud in the package.
For another node not showing video info, I tried to reconfigure jumper J46 to 2-3 and then to 1-2 to reset bios, still not working. I bought a low end video card Dell NVIDIA Quadro NVS 290 256MB PCIex16 Video Card
recommended by grfxlab. Probably my GT620 is not early enough. Thanks for the forum members' help.