PSU needed for 3870x2 Quad-Fire?

[stonedzen]

I'm interested in setting up a dual 3870x2 "quadfire".

The Antec PSU Calculator said I needed at least 800watts. However, it also says I need at least 670watts for my current system which is running on a psu that is only 430watts.

Any opinions what minimum power I should be running? I know my current psu will not be enough, and was wondering if anyone knew any decent (and affordable) psu's that could run two 3870x2's along side my existing hardware. Also know that I am aware that 3870's are dated, but I am getting a second one in a hardware trade (please don't insist I just buy a new card).

Here are my specs:

-AMD Phenom II 955 BE OCed to 3.6 on 1.45volts
-G.Skill Ripjaw Series 2x2GB DDR3-1600 cl 7-8-7-24
-MSI GD70-790FX Atx with 16x/16x crossfire
-HIS Radeon HD3870x2 256-bit 1GB DDR3
-Two 7200 HDD's 700GB total'

Thanks

 

[wa1]

http://www.newegg.com/Product/Product.aspx?Item=N82E16817139011

 

[stonedzen]

I was thinking something like this:

http://www.newegg.com/Product/Product.aspx?Item=N82E16817371022&cm_re=antec_truepower-_-17-371-022-_-Product

or,

http://www.newegg.com/Product/Product.aspx?Item=N82E16817371026

Both have a solid 25amps per 12v rail, 2-6pin and 2-8pin connectors and 750watts continuous. Plus they are almost $70 less than the one suggested. Any other opinions?

 

[wa1]

well, i suggest that cause it has big power, surely it will last longer, very long...
anyway, both of your options are good...

 

[nforce4max]

Two 3870x2 are very power hungry but a high quality 750w unit can do it but the power draw of the cpu can be the wrench that could be problematic. If you are able to spare the extra cash I suggest a 850w + unit.

 

[stonedzen]

Considering I'm currently running the entire setup with one 3870x2 on 430watts, and all I'm adding is another x2...do I really need to add an addition 420watts to my supply?

Its not that I doubt anyones advice, it just seems like it may be overkill and I'm on a tight budget.

Is it the general opinion that I could run the quad CFX with a decent antec 750?

 

[nforce4max]

Get PCwizzard and check your cpu's estimated power consumption under the cpu and clocks tab when it is under load. Mine uses a meager 88w but it is all to common for people buying those 140w samples. By the way psu calculators are poor measures of ones needs.

 

[stonedzen]

I just got PCwizzard but I cant seem to find the cpu and clocks tab you're talking about.

 

[nforce4max]

Once you load it clock the black looking chip tab, then click frequency. After that scroll down to ware it says thermal information. It will say the stock power and if you are overclocking like the rest of us like you have said it will show a higher than stock rating based on your clock and voltage.

 

[stonedzen]

Hmmmmm found what you're talking about and it says I'm only pulling the stock 125 watts. However it also says I'm running 1.35volts in my cpu, when I'm actually pulling 1.45volts for my overclock (cpu-z and HWmonitor both confirm the 1.45voltage)

Does this mean PCwizzard isnt showing my actual cpu power usage?

 

[nforce4max]

Only estimated, it shows stock wattage and shows current wattage. What is your current wattage?

 

[stonedzen]

Jumps between 124.99 and 125.00 watts

My overclock is quite mild atm, only 3.6ghz on 1.45volts.

Back to the original question, do you think a solid 750watt would suffice? The two I listed above are available at a local store and would have a 60 day in store warranty on top of the manufacture warranty. The first is $134 and the second is $148.

 

[nforce4max]

Jumps between 124.99 and 125.00 watts

My overclock is quite mild atm, only 3.6ghz on 1.45volts.

Back to the original question, do you think a solid 750watt would suffice? The two I listed above are available at a local store and would have a 60 day in store warranty on top of the manufacture warranty. The first is $134 and the second is $148.

Must be a bug but don't worry about it, a 750w Quality unit just might do it. Its the load that I worry about but go ahead and get it.