Is this mining speed right

[linlinsome]

I am mining with four Dataland R9  270X  cards using cgminer. The hashrate of this kind of card  can  reach more than 400KH/s per one.  But my rig can only reach about 300K per card, and the total WU is about 900K.  When i set the Intensity to more than 13, HW uprising quickly, so i only can set all four at 12.

how can i increase the hashrate of my rig.
BTW: i use the win7-32bit OS,  is win7-64bit better?

i've set the gpu-engine to 1000M.

is there any other para i can set in the cgminer.conf  to increase the rig's function?

[dzsudzsu7]

Do you have enough system ram?

[linlinsome]

KINGSTON 4GB DDR3

[newway]

win7-64bit is better but you need minimum 8GB ram