It may operate just fine for awhile, but I would not want to stress my system with a grossly underpowered power supply. If you try to play Witcher 2 like this, watch diligently for overheating. That puny little power supply is not only being called upon to power that video card, but also all the other components on your system. Be very careful if you don't upgrade it. Sometimes they just overheat and die all by themselves, but it's not unheard of for them to blow the entire motherboard.

And I would not put it on a list; I would shut the computer off and not use it until the new power supply is installed. That so-called maximum wattage used by the card may not reflect what it needs when stressed by a game like Witcher 2. There is a reason the minimum power supply required for this card is 450 watts.

Hope you don't get buried too deep! Akasa is not a brand sold in the US, so I hope it's a good one for you.