The main hardware items are:
CPU : Intel Xeon E3 1230 V2
MB : MSI Z77A-G43 ~ 2.4 version BIOS
RAM : G.SKILL 4GB 1600 x 2
SSD : OCZ Vertex 4 128G~220.127.116.11 firmware
HDD :WD 80G HDD X 2 Raid 0
Graphics Card : XFX 7970 3GB
PSU : Seasonic X560 560W
Windows 7 ultimate 64bit was installed on SSD, and a partition on HDD was allocated for virtual memory.
It ran everything with no problems. but when I log off, the computer was freezes, and monitor didn't get signal. Then,try to press 'Num Lock' button, not responsing, seems the keyboard already doesn't work. I also have tried to unpluged the cable of keyboard and repluged it, Keyboard still doesn't work.
The computer back to normal after restart by pressing 'reset' button, but this trouble will occour again just need a logging off.
Don't log off, or put the computer into standby, or the HDD into standby, or enable the sleep and hibernation modes.
The monitor standby can remain enabled, that's all. Otherwise, shut the system down instead of logging off, sleeping, standby or hibernation.
Disable system standby in the windows 7 power profiles. Leave monitor standby turned on.
It's a good idea to disable standby functions of the mouse and keyboard also. The system may automatically turn these devices off to "save power," but then the system is frozen...will freeze unexpectedly.
It's a bug which seems to affect some computers...and just work around it by not using those functions.