I bought this two weeks ago now to upgrade my old 8600 gts and what a step up this was, armed assault in very high quality,batman arkham asylum in highest quality and fallout in the highest quality all at 1280x1024 which is the resolution my monitor supports. It eats all these games for breakfast and still has room for more.
My only gripe about this is the fan noise which is real loud,not quite hairdyer loudness though but the loudest card i have heard.
The card comes with 1gb ddr5,850 mhz core clock and a memory clock of 975 MHz. I have read that these are great for overclocking with up to 14% performance increase which is huge i have yet to try this out though.
the card is very easy to install i recommend at least a 550 watt power supply for this though as it is a beast of a card,it is dual slot design and requires two pci-e power connectors which is a strain. The box set comes witha a few handy convertors, it has a dvi to vga adapter for older monitors,dvi to hdmi converter and the card has an onboard sound controller so it is the only graphics card to support both video and sound through the hdmi dongle, also supplied is two pci-3 to molex adapters for those with older power supplies which only has molex adapters.
this card is really impressive and at the moment i have no hold backs in any games even crysis warhead is on high detail.no complaints at all except the noise.
One last thing is that now ATI have relased the 58xx series these cards will be ati's new flagship range supporting the upcoming directx 11 and stunning performance,people who want to future proof or are hard core gaming enthusiasts should look to these cards.
edit:i have noticed this is for the OC edition,it should be for the standard refence 4890
I presently have 2 of these GPU's running in my rig. In my opinion ATI presently have the upper hand on NVIDIA with regard to 'bang for buck' at the moment.
Very generally, 2 of these cards will outperform a GTX295 in most games, not all but most. A single 4890 will perform similar to a GTX275 and in some applications it can be compared to a GTX285.
I have had no serious issues with these cards. They run hot, but that is how they are designed. Catalyst Control Centre (CCC) can be easily tweaked to alter fan speeds if you start get worried about the temperatures. Alternatively you could use Rivatuner top set up your own fan profiles.
The cards are easily overclocked in CCC as well. Stock clocks are 850/975 and I have mine running at 960/1075, without a voltage mod. They can be run higher with a volt mod but you have to really crank up the stock fan to keep temperatures down.
Be warned the stock cooler on these cards is LOUD if you push it over 50%.
As far as reference 4890's are concerned this is a good product that can be easily over-clocked. Look for good prices on these as 'Evergreen' lands soon.