Can i use ati radeon 5570 1gb ddr3 on my dell vostro 200slim

i couldnt' find info on your particular model as far as the card fitting, however all the rest of the vostro pcs i read about requered low profile cards , the best ati low profile cards out now are 5570's; however your model MIGHT be able to accept regular cards in your model ... there just isn't enough data published online about your series that i[ve seen to give you a difinitive yes on a full size card. good news is if you go with a low profile and no overclockign your psu should be abel to handle it.

its a slim cabinet. pnly low profile crds would be possible. but can a 5570 hd run on my 250 watts psu

Yes, it should run on 250W PSU, don't worry about that...  

Thank U  

why do ati give a min power req of 400 w then

can i play demanding games like crysis with that card and that 250 w psu

Crysis? No, that's a very demanding game, with your current system+HD5570 i guess you can play it with LOW setting, depend on what resolution...
You will be able to play crysis, but with low setting, that's all.
But you will be fine with the other games, don't focused just on crysis...  

asus or sapphire which is a better brand

They are both good brands. Between those 2 I would just chose based on price. If you are in the US this card is also a good brand and it has an impressive rebate;
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

in case of ati 5570 which may be better.i think asus is associated with a loud fan

Low profile cards are generally have a "loud" fan...

is asus version of 5570 good

i bought an asus eah5570. but some videos which ran ok on 4350 is having pixellation on 5570. why wud this happen provided 5570 is much more powerfull than 4350

Pixelation should only be a result of the resolution of the source file being lower than the resolution you are using. The card really shouldn't have anything to do with it. Are you using a higher resolution now? If not it could just be that you are looking closer at the image detail looking for issues with your new card but the issue was always there all along.

Best answer selected by joemathew85.