Is that a pre-built computer? Must be since its an un-named OEM motherboard. So without the name of the whole computer, cant do much.
But if its anything recent (P/H61, Z/H68, Z/H77, probably most LGA775 chipsets), the top PCI-e slot should be at 16x.
Even if its not and only 8x, I doubt it would bottleneck the GPU, the cards you are getting aren't all that powerful.
An image of the whole motherboard may help. Brand logo's or specifications on it, that sort of stuff. It will also tell us if it has a standard ATX layout, so we can figure out if its a board unique to that pre-built or if its a proper consumer motherboard.