That mobo has 1x pcie x16 and 1x pcie x4 and he wants to buy another Sapphire 5670 gddr5 512mb. Is the x4 slot powerfull enough for that card? We got a very good deal on that card so only a slight improvement would still be ok but will it work at all? cause i know the x4 is made for discrete GPUs and the 5670 is somewhat faster that your average low-end gpu. The guy at the shop said he can't guarantee it will work at all.
Will it work? Yes, if you use the bridge provided and fresh install the CCC driver after the 2nd card is in. However, I don't think you'll be happy with the FPS results. I have a Biostar board (x16, x4) and a i3-2100 with a HD 6850. I tried a 2nd HD 6850 and found the results were unsatisfactory. Some games had a marginal increase in FPS, while other actually lost FPS. It was like the slower slot was holding back the faster slot. I'm back to just 1 HD 6850 now.
Maybe the HD 5670, being less demanding, will work better with x16, x4 slots, but I'm afraid to recommend it.