download a copy of the mobo manual from here
http://www.gigabyte.com.tw/Support/M...ProductID=1914
use the related links section of that page to get the latest drivers for chipset, audio, etc...
-verify the 4pin connector ATX_12V is installed (2 black, 2 yellow wire) it powers the cpu and system will not start if absent.
-clear cmos by removing battery and shorting pins CLR_CMOS for 20 seconds, re-insert battery.
-use only one ram stick till system tested and stable. if does not powerup then remove ram stick, verify external speaker connected to correct F_PANEL pins and powerup to see if get beep error.
-------------------------------------------
Always give full details for parts (make-n-model) mobo, cpu, psu, video
Both Athlon 64 Sempron 3400+ and Athlon 64 3400+ are supported for this mobo and use a System Bus speed of 1600(MHz).