Which graphics card is better?

I am not sure but maybe the 4890 will be the better choice even though it only supports DX10, but since those cards aren't exactly good by today's standards (when it comes to gaming) the fact that the 4890 doesn't support DX11 ain't that bad since i would avoid using DX11 features in any game using any of those cards to keep performance somewhat respectable.

I know the 4890 used to be GTX275's rival, so it will surpass the 250, i also remember that my GTX275 was much better than any 5770, so the 4890 will also be much better and the 6670, if i am not mistaken is on the same level as the 5770, not much better or worse. So as i said, the 4890 is probably the better choice and i would even risk saying that is better by far.

The 4890 on newegg is OEM. I don't want an OEM item. So, I think I have to pass on that one.  

6670

http://www.newegg.com/Product/Product.aspx?Item=N82E168...

why not this its a few steps up for the same price

HD 6670 is almost the same performance as HD 5750, HD 6770 is a bit faster.
Best of what you listed is the HD 6670, other models shouldn't be considered due to the absence of DX11 support and GDDR3 memory.

The 4890 is DDR5 and i just cant see any of these cards being able to take advantage of their DX11 features with a nice performance, at least not in games, as far as i have seen DX11 features like tesselassion and some other stuff is only available on very demanding games and most of those features are for high or ultra settings, so DX11 support on these cards don't make much difference if any at all in my opinion. So i would still go for the 4890 if he manages to get one for the same price as the other cards he mentioned. But that its just my opinion...

We\ll assume that the HD 4890 is fully supportive to GDDR5 transfer rates, what about the power consumption, heat & noise issues ? the HD 4890 is more than a reference card, the OP will get it used, are you guranteed that it won't cause any problem ?

Besides, who said that DX11 is useless, Crysis 2 has the most implementation of DX11 and you can for sure tell the difference between DX9 and DX11 in shadows, texture quality, sharpen edges..........

the 5750 is the best choice out of those cards.

to play crysis smoothly in dx11 you need a gtx570 or better.......... none of these cards come close, so in this instance, dx11 does not matter, you wont be turning it on due to low performance.

No one said there were no differences... but run Crysis 2 with it's DX11 features enabled on any of these cards... You will probably be able count the fps by yourself without fraps...

Then run the game with DX10 and compare the performance of a 4890 to a 6670...

This comparison is not trustworthy as the diference in real life is as big as the specs difference but it might give you an idea of how a 4890 is superior to an 6670...

http://www.hwcompare.com/10896/radeon-hd-4890-1gb-vs-ra...

Maybe i should have searched a little better but these card are not even comparable so i doubt i'll find a decent comparison.

As far as i can tell a 4890 packs more muscle than a GTX-550...

http://www.hwcompare.com/9751/geforce-gtx-550-ti-vs-rad...

I think I'mma get the 6670... It doesn't even need extra power!

EDIT: Actually, the 6670 has a PCI express 2.1 x 16 interface. I heard that it wont work if your bios can't detect it. My motherboard only has pci express x16 interface. I guess i'll get the 5750.

A 5750 is a bit better than a 6670 but it still get's trashed by a 4890... so my sugestion is to still get a HD4890 or a GTX460 for similar performance with DX11...