My ECS 6100SM-M mobo runs it's PCIe slot at 8x although it's the only PCIe slot on the board and is where the GFX card would be placed. I don't understand why this manufacturer decided to run the 16x slot at only 8x??? what's the point???
If you go to ECS's website http://www.ecs.com.tw/ECSWebSite/Products/ProductsDetai... and look up your Mobo you can clearly see that the slot is designed to run a X8 they just elongated the slot so you could put a Graphics Card into it. I really wouldn't worry about it because only if your installing a Radeon HD 4850/GTS 250 or more powerful card will you see a very big performance decrease.