Get the 4890, or any single most powerfull card you can afford. http://www.abit.com.tw/page/en/motherboard/motherboard_...
Mainly because your motherboard has the second PCIE slot at x4 which will be a huge bottleneck if you want to Crossfire. And secondly the motherboard dose not appear to support SLI anyway.
based on what the idiots on eBay are asking (and getting - ugh) for an HD4890 ($140-$170) I'd go with an HD5770 as it's about the same as an HD4890, same general price (for the 1Gb versions) and you'll get DX11 and EyeFinity (in case you ever want to run THREE monitors instead of two). I can't speak for the nVIDIA side because I haven't bought or built anything using the green team since my old 9800GTX, but given a GTX 260 is the same speed as an HD5770, but the cheapest one is $50 more, I'd stick with ATI.
That said, you'll need to OC that Q9550 to get the most out of the 5770. I built a Q9650 with it and at stock speeds the processor was a bottleneck. Bumped it up to 3.6GHz and saw an immediate 10-15% bump in benchmarks.
based on what the idiots on eBay are asking (and getting - ugh) for an HD4890 ($140-$170) I'd go with an HD5770 as it's about the same as an HD4890, same general price (for the 1Gb versions) and you'll get DX11 and EyeFinity
No, it's not the same. And $140 for an ATI 4890 would be a decent price.
A 5770 performs almost equal to a 4870. A 4890 performs about 15% better than a 4870 or 5770. A 4890 has the 5770 beat in terms of raw power.
A GTX260 is roughly equal to a 4870 or 5770. A GTX275 performs roughly equal to a 4890.
The 4870, 4890 and 5770 are in teh same row. I've built an X4 965BE OC'd to 3.8GHz and had a Q9650 OC'd to 3.6GHz (just sold it with the 5770) and, while building, happen to have all of those cards around, plus a 5850, and tested them just for ***** and giggles. All three of the cards were within 5-7% of each other in 3dMark06, 3dMark Vantage, and Crysis, while the 5850 was (obviously) about 20-25% faster. A 4890 is nowhere near 20% faster than a 4870, at least not on the two machines I've tested it on.
The 4890 IS faster, yes...but by 7% in Vantage, 13-15% in Crysis, 9%-10% in MW2, etc... 20% is pushing it. I exaggerated a bit, but "about the same" is...close. :-)
The bigger issue, though, is that you're going to play hell finding a 4890, and I've never been one to trust used graphics cards off of eBay. If you can find one new for $140 then heck yes...great deal. I would just rather go with a 5770 or a GTX260. The GTX275...forget about it. Out of stock everywhere except for one WAY overpriced one on NewEgg. Plus, like I mentioned, with a Q9550 he's not even going to be able to push a 5770, let alone a 4890 anyways without a major overclock (and even then???), so a 275 would be WAY overkill.
Thanks guys. I guess the bottom line is the 4890 (if I can find one) is the top of my heap primarily because of the Q9550. Given the present state of my machine (motherboard and cpu) is it better to stay at the 8800gtoc or at most the HD 4870?
The 4870s are still available on NewEgg - for as low as $155. However, the 5770 is faster and is only $10-$15 more. Plus, you get DX11 and EyeFinity. Like I mentioned, I can push a 5770 to higher bench scores than a 4870 in identical machines (tried it twice) but, admittedly, not by much. IF you can find a 4890 and don't care about DX11, and you can get it for under $150, then that's your best bet. Otherwise, go with the 5770 - you won't be disappointed. At 1600x1200 all of those cards will pretty much max out any game WITH AA and AF so you should be happy.
The last benchmark run I have on an 8800GT OC (from EVGA - pretty much like yours) was with a Q6600 OC'd to 3.0GHz (9x333 - slightly faster than your Q9550 which is 8.5x333). Using 3dMark06 as a reference, my scores went from 12,420 with the 8800GT OC to 14,300 with the HD4870 - a nice little 15% bump. The processor was a bottleneck, though, because going to a Q9650 OC'd to 3.6GHz (9x400) got the score to 16,172. So...15% bump going from an 8800GT to an HD4870, and another 13% with an upgraded processor and an overclock. With any of these cards (the 5770, 4870 or 4890) you'll be happy...but you'll be happier if you can get that Q9550 up to a 400MHz clock (8.5x400=3.4GHz). Then...they'll shine.