Test if your PC can run GTA IV

[Hitman]

Hey, the GTX 280  has 1024MB of GDDR3 Ram too

The GTX 260 has 896MB

Well, there are some differents between GTX series and HD 4870:

both of them have to increase their  bandwith in GB/s.
You can increase the bandwith in 2 ways:

- make the memory interface bigger
- increase speed of memory

a little metapher, its quite easy but you can understand it better then:

see the data the card renders like  water in a river - if more data runs down the river, you have a bigger bandwith.

to increase the bandwith, the water can run either FASTER (thats the memory speed) or the river can be made more wide, so more water runs through it at the same time.

Its like this:

GTX 280  memory speed: 1100MHz (1100 GDDR3, has 2 cycles so its 1100*2 = 2200MHz effective speed)
HD 4870X2 memory speed: 900 MHz (900 GDDR5, has 4 cycles so its 900*4 = 3600MHz effective speed)

But now the GTX 280 memory interface is: 512Bit
while the one of HD 4870 cards is: 256bit

Its just that ATI has chosen to increase memory speed to increase the bandwith while NVidia doubled the memory interface - in pure power, there are like 5% difference between GDDR5 and GDDR3 - dont be blind just because you see MHz

Both have almost the same bandwith, so thats no advantage or disadvantage for none of the cards .