Lets make it simple , ATI = RED , NVIDIA = GREEN. Both are big players in the dedicated performance market.
Well, as most PC users who has been waiting for new stuffs from Nvidia sure heard of the new "Fermi" architecture GPU. Just recently a picture was posted on DriverHeaven showcasing a GF100 Fermi GPU running a 24inch 1920x1200 running a 8pin + 6pin power connector.
What is the new Fermi about ? well, in respond to the current king-of-the hill ATi HD 5970, Nvidia's fermi was in development secretly (lol) behind the red's release. To be honest, Nvidia is late in the race but the previous cards is a few steps ahead of the red's time. Let me explain why.
Lets start from a few years back during the Nvidia 6xxx series card and the ATi Xxxx cards. (I'm not going deeper back, as it's unnecessary)
The Nvidia 6 series lowest end was the GF 6200 and the ATi's lowest end was the X300 , both is on the same level but performance varies, Nvidia is a clearly ahead of the ATi low to mid end in terms of price/perf back in the days, but on the high end the Nvidia 6800 is going head to head with the X800 where the ATi's highend is cost effective but simply lacks of shader model 3.0 where Nvidia excels. This is the time when the heat starts.
Not too long after the Green's 6 series made a huge bucks selling the 6600 and 6800 like hot cakes, they made a new 7 series right out based on the same design but with more power, running 20+ shaderpipes on the high end and running more cooler and faster than the Red's X800 and X1800, Red did something about this and they made a card that could come close to it but fails to keep to heat and power consumption down. This is the part where Green starts to pull further than Red's position.
Right after the end of the old pipeline tech, both company jumped into the shader/stream processor tech where the GPU itself is a multithreaded GPU (in layman's term). The Red's was indeed still behind the green with its HD2xxx series cards, its hot, its eating too much power for price/performance and the crowd still prefers the Green's 8 series, from this time on Nvidia started to make lots of money for further research. Lets make a table for it so i can fast forward without posting a wall of words.
ATI X300/600/800 >< GeForce 6 series
ATI X1300/1600/1800/1950 >< GeForce 7 series
ATI 2xxx Series >< GeForce 8 Series
ATI 3xxx Series >< GeForce 8 Series
ATI 4xxx Series >< GeForce 9 Series (8 in 9's disguise)
ATI 4xxx/5xxx Series >< Geforce GTX2xx Series (certain 2xx series is also an old 8 !)
ATI 5xxx/6xxx ? >< GF 100 (fermi)?
As you can see, the rows above contains generations of card from both big players. Nvidia has been using the GeForce 8 series for the three continuous battle without making much change other than making it more smaller and power saving, imagine how much have they made during these time.
Lots of review sites thinks Nvidia is losing this time, well ? they're not and I hope not (IM NO NV FANBOY, but they do make innovative stuffs), coz whenever there's competition in the market, there will be a rock bottom price fight and the winner will be the consumer. Power to the people !