Re: ASRock 890GM Pro3 R2.0 motherboard Graphics Ugrade Help
1: no, the memory of the gfx card has nothing to do with your systems.
2: it comes more down to your PSU then your mobo, and a 750W you got pretty much anything open up to dual gfx cards (not checked out your boards pcie slots, but assuming you got atleast one 16x PCIe slot)
3: shouldn't be any problem at all
4: I'd just disable the onboard and get a decent hd6870 with a slight factory OC and modified cooler (I'm quite happy with my HIS IceQ). I would get one with 2gb ram though
5: x16 is the speed of the slot, 2.0 is the generation. There isn't really any difference between 2.0 and 2.1, and the cards are up and downwards compatible. Pick the card you like best.
My advice - never visit a short-url, no matter who gives it to you. You can't trust any source at any time when you don't know your target
Whitey: ROG Crosshair V Formula/Thunderbolt, AMD 1090T @ 3.2GHz w. NZXT Havic 140, Corsair XMS3 1333 8GB kit, HIS IceQ X HD 6870, Corsair Force GT 120GB, OCZ Vertex4 256GB, Kingston SSDNow 16GB, Samsung 500GB 3½" in casedock when needed, Chieftec Nitro88+ 650W, NZXT H2 White, 3x Asus VS248 24"
Snuggles: Zotac Zbox HD-ID40 (Atom d525, worst purchase ever on cpu), Patriot Pyro 60GB (Thanks to Tweaktown Giveaway), 4GB 800' DDR2 SO-DIMM
Bcube (NAS): ASUS F1A75-I Deluxe, AMD A6-3500 @ 2.1GHz, LSI 9240-8i (M1015) controller, GSkill Ares 1866 8GB blue kit, 4x Seagate SV35.5 2TB, 1x Seagate Barracuda 1.5TB, 1x Samsung HD103UJ, 1x Samsung F4 2TB, Temp. Rebel9 Alu case, Corsair H60, 2x Icy Dock MB973SP-B, NZXT UI01, Enermax T.B. Silence on docks and cpu, Aurum 500W gold PSU. (Draws 65W average, doesn't peak above 100W at any time)