i think i found the answer from intel themselves-
read what's written underneath:
http://www.intel.com/content/www/us/en/chipsets/mainstream-chipsets/g41-express-chipset.html
(ddr2 8gb maximum / ddr3 4gb maximum)
now the question is why do motherboard manufacturer still claims it's 8gb max...
i could understand this mistake for the combo boards which have both ddr2 and ddr3 (not simultaneously)....