Seasonic S12II-620 vs X-650

[Michaelius]

Hey guys

I'm looking to upgrade my 4 years old Chieftec GPS-450 (also known as Delta GPS-450A) because of insane noise it produces (and efficiency <80% doesn't help on power bills too)

I need something that would be resonably quiet and have good efficiency (rig on 60-70 hours per week doing BOINC so 100% cpu load all the time).

Rig will be:

X6@ 3,8-4,0 (depending how far i can go with 1,4V) , radeon 5870/gt470, 2x ssd +2-3x 2,5" laptop drives, xonar (after i finish all the upgrades)

Case will be Fractal Design 2

After reading all the reviews on [H] , johnyguru and hardwaresecrets to the point of brain melting i arrived at conclusion i want seasonic

Now my choice is S12 II-520W Bronze for around 75 euros
S12 II-620W Bronze for slightly less than 90 euros
X-650 for 150 euro

X-650 has around 3-4% better efficiency, modular cables, 5 year warranty instead of 3 but honestly that's insanly expensive for a power supply.

Do you think it would be really worth it ?

And wouldn't X-650 suffer from being bottom mounted when in fanless mode (assuming load would be so low to ever get into fanless mode)

PS. I could also get Enermax Pro87+ 500W for 125 euros but that price seems to be not too atractive.

 

[Tsumi]

With the HD5870, you'll be fine with the 520 watt power suppy. With the GTX 470, you might want to look at the 620 watt power supply (the GTX 470 consumes about 40-50 more watts than the HD5870). Although I think the 520 will be able to power both graphics cards just fine.

 

[anthrex]

Tsumi is correct. I went with the X-750 because for me silence is paramount in my upgrading from now on and wanted a solid base for that with the X-750. If you aren't worried about that and want the modular cables check out the Seasonic M12II. Not sure what the pricing for that in Europe is, but if its available shouldn't be too much more than the s12

 

[Michaelius]

Well with power it more comes to working into 50-60% psu load efficiency sweetspot.

Reading todays x-bit article they have X6@4,0 1,5V + 5870 at around 300W DC.

 

[Tsumi]

The power efficiency curve is different for each power supply. In general, it is true that the sweet spot is around 50-60%. However, for some power supplies, it might go from say, 86% efficiency to 82% efficiency when going from 50% load to 100% load. Others will just go from 86% to maybe 84-85%, and at that point, there really is not too much of a difference (maybe 5-10 watts for a 500 watt power supply). I can't justify the cost of a larger power supply if the difference in efficiency is about 2-3%, it would have to be maybe 5% or larger to really make an impact. The X6 will consume 150-170 watts at the most, and the HD5870 will consume 180 watts at the most. There really is very little chance of you hitting 100% load, you're going to hit probably 80% load with a 500 watt power supply.