4850 crossfire on a quality 450W PSU?

[carpenter20m]

Hi, I have an old system, which I am planning to upgrade. The only things I want to keep are the hard drives, the DVD-RW, my 4850 and the PSU (it's a Corsair 450VX).

I was planning on getting an i5 or a high end Phenom II. My question is, do you think that my PSU with 33A on its single 12V rail can handle two 4850s (since I am planning on getting another one and crossfiring it)? I know the requirements ask for a 550W PSU, but mine is a good one.

Do you think it can handle it? (I am not planning on overclocking, by the way, nor will I put a lot of hard drives in there. 2 is enough).

Thank you.

 

[Guest]

My advice, yes one 4850 is fine with that psu, but you will need more power to crossfire, what you dont want is your PSU running at full load constantly, and you will be with 4850 cf and i5 or Ph11.

If your PSU goes pop due to constant load like that it could take other parts with it!

Now that corsair is a good psu at 80% efficiency, but for your two 4850 you are looking at 216.7 watts load and 18 amps

Now lets add everything else, just approximates

GPU 216
CPU 125 (Phenom, will be less for i5)
Chipset 60 (nvidia older chipset, they are now more efficiant but as example)
HDD x2 20
DVDrwx2 20
Mem x4 12

Total = 453

Now granted you may be able to go lower than this with i5 but you will still be near 400w on a 450w PSU, the corsair 650tx would be a good PSU for you, not overkill but enough juice for 2x4850

http://www.tomshardware.com/reviews/geforce-radeon-power,2122-7.html

Good reference article, although a little out of date

Hope this helps, if so please best answer

 

[wh3resmycar]

im using the same psu (vx450) with an older process (q6600, consumes more power than an i5 or phenom2) a gtx250 and 3 drives. been running it more than 10hours a day the past 2 years.

just dont listen to the guy above. obviously the guy is rails-challenged.

 

[JofaMang]

The question is for Crossfire, not single 4850. Single its obviously fine, I would not use it for crossfire, just asking for trouble.

 

[cybot_x1024]

get the raidmax 530w psu as an absolute minimum to run that setup.
As much as the 12v may have 33A on it there's also the other rails that have to balalnce depending on all other components utilising other rails(most specifically the 5v) because you could easily exceed the max allowable power draw for that PSU for the combined 12v & 5v rails.