Hello!

I need to upgrade my PSU. I have Radeon 4870 and in next month i will buy another one or 4870 x2.
I know this PSU will be enough for 2 4870 in CrossFire (i hope ) but what about 4870x2?

In our country is the cheapest 1000W PSU a lot more expensive than 750W
.
750- arround 90 EUR
100o - arrounf 160 EUR

Should i buy 750 or 1000?

i think you will be fine wiht the 750 just make sure its good PSU like corsair like PCP&C

The TX750 is a beast, you will be fine.

As you can see here, an overclocked QX9770 with an X48 motherboard and a pair of 4870s in Crossfire draws a maximum of 421.5W. Add in another 4870 and you'll be around 670W of power draw. As you can see here, the TX750 will handle that without breaking a sweat.

I have a TX750W. Never had a problem, plenty of overhead room. One review I saw when shopping for it stressed it up to 950W with just under 80% efficency, then the breaker blew. They never did find out how high it could go.

Great. You guys help my a lot!

I do not think it will be enough
I tried ti calculate here
http://support.asus.com/PowerSuppl [...] uage=en-us
When I select 2 cards HD2900 (cause 4870 is not listed) the result is 950W
And if I select 2 cards 9800 the result is 850W
Other selection
1 mobo
E8400
2 sticks RAM
3 (HDD/DVD)
1 PCI card
5 Fans

PSU calculators are not that good. Especially the one you used.

Like homerdog says, 2 4870 in crossfire and an OCed QX9770 only consume 420W.

I'm not a GPU/PSU expert, but from what I understand it's more of an Amperage thing than wattage. I can't imagine you'd need 850W to run 2 video cards.

Well
I tried here and the result is 635 W
http://www.extreme.outervision.com [...] orlite.jsp
Cheer up

That is absolutely ridiculous.