Help - ECS Geforce6100sm-m

[rafail90]

I have an AM2 ECS geforce 6100sm-m 1.0 motherboard with a pcie x16 1.0 slot (works in x8 mode), and decided to install a newer graphic card on it.
This card is eVGA geforce 8400GS PCIe 2.0 512Mb GDDR3.
By all means, a 1.0 slot should support a pcie 2.0 card.
In my case, i just get a blank screen when i press power button to start my computer.
The only sign of life of this card is that its cooling fan rotates, but screen remains blank.
I tested it on another old computer, and works.

I contacted ECS, and after all those steps i followed, they claimed this card might not be supported by my motherboard.
I was wondering...is it a hardware problem or a bios problem?
Is it possible that bios can't support PCIe 2.0 cards?
Unfortunately, i don't have any other version 2.0 card to test.

Help would be appreciated.
Thanks.