Which Size PSU You I Get

nheather

nheather

nheather

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Joined
19 May 2004
Posts
942
Location
Horsham, West Sussex
To cut a long story - I need a new PSU.

This is what I will be running

Gigabyte FX790 MoBo
Phenom II 955BE (overclocked to 3.4 or possibly 3.6GHz)
2 sticks of 1600 DDR3
HD4890 GFX - running at 850 for now but may push up to 900

1x SATA HDD
1x SATA DVD RW
1x IDE DVD Rom

2 case fans - 80mm
1 CPU fan - 92mm
1 PSU fan - 120mm

When I plug this into a PSU Calculator it comes to about 357W. If I crossfire another 4890 it comes to 448W.

But I don't know how much to trust this.

Now I haven't bought a PSU for ages so I came expecting to pay around £50 for a good one.

But I've found that I've got to pay around £65-£75 for a 650W.

I like the idea of the single rail on the Corsair TX 650W - I'm more than confident that this is enough power for now (single 4890) but

(i) what if I were to add a second 4890 at some future date

(ii) what if I were to replace the 4890 with a 5850 or 5870 at some point

650W (52A on 12V rail) seems ample but if that is the case I simply can't imagine what people do with 1000W PSUs.

Perhaps I should buy a 750W but then I'm looking at near £100 which is a lot more than I wanted to spend.

What do you think?

Cheers,

Nigel
 
TX650 is more than enough for your needs, you will be fine crossfiring 4870s or 5870s with that. The TX750 will copes fine with crossfiring 4870X2s.

If you intend on overvolting and overclocking everything a lot (cpu and graphics) and watercooling you may need 750-1000W when crossfiring dual gpu boards.
 
the PSU calc thing is trash...it uses straight TDP values and just adds them together.
Click to expand...

I'm not wholly convinced by them either but having said that I went looking for some idle\load power info for the HD4890.

I wasn't too successful as the tests I found just quoted the power for the whole test system - but they were around 330W on load which pretty much ties up with what the calc came up with.

Cheers,

Nigel
 
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