ANSWER FROM NICK AS HE CAN'T LOG IN AT THE MOMENT
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I dont want to keep bothering Dave but I wanted to post this to you.. and everyone else about PSUs and they one you are looking at
I want you to read this carefully.. I posted it with very easy to understand terms and calculations so you and everyone else understands how PSU shopping should be done.
Your Pixxo
http://www.pixxo.com.tw/WebForms/ProductView.aspx?id=193 Its either 500/580 or 650
If it IS a 550 then it may be one of their older units and that may be WORSE! I am going to ASSUME it’s the 580 and not a 550 for4 this.
This is a GENERIC PSU company and they make cheap PSU’s for other companies as well.
Let me show you something and you will see why what you are about to do is a big mistake!
First of all, it is a MULTI RAIL supply.. meaning you do not get 100% of the amps available on the unit. Just because it says 580 does not mean 580 will be delivered.
Lets look at this very simply and from here on out you will know what to look for.
If you have no choice and you must buy a cheap multi-rail PSU you must first look at the amount of power your system needs. For this you are looking at a 9800GTX and that does NOT include the system itself, just the video card.
The 9800GTX needs a MINIMUM of 24A of power. You should ALWAYS try to go 25% higher on the power needs to make sure
A: As the PSU gets older its current DROPS. Over a 1-2 year period if its cheap you can expect a 10% loss, easy with another 5% loss for HEAT
B: As the PSU gets HOT the current drops. With a cheap PSU that means another % of loss as it heats up. Therefore the 25% HIGHER in power takes that into account
Now.. for the Pixxo 580 unit you have 12v+ RAILS that are rated for 15A each. Is that really 15A? NO!
Look at the EFFICIENCY RATING - And do NOT ASSUME the HIGH RATING of 85%... at FULL LOAD you get a MAX of 80% and with a CHEAP SUPPLY the HEAT and TIME will drop that further!
So we have a video card that needs 24A
We have a PSU that has 15A on 2 12v plugs that = 30A Sounds good right?
30A MINUS 80% FULL LOAD = 24A THE MINIMUM THE CARD NEEDS
Take another 10% for TIME and ‘possibly’ another 5% for cheap component HEAT and guess what, you have 19.5A = (30A x 65%) with a video card running HOT and CRASHING due to LOW CURRENT and you have a PSU running HOT and dropping even MORE power to the rest of the system!
At first you may not see the damage and the issue but as the supply runs over time you are 3A TOO LOW for the card
And the rest of the computer is starved for current as well
So is that 30 dollar supply worth it in this system?
NO!
Even their 650 watt supply is JUST BARELY ENOUGH!
It has 12v+ 18A x 2 = 36A x 65% (includes time) = 23.4A - just BARELY enough!
So you can see now what you are paying for.
The supplies that I picked are SINGLE RAIL. That means not matter what the 12v will always be a constant on the line. It too must be calculated the same way however the manufactures post specs for their EFF CURVE in which they will NOT lose as much current over HEAT, LOAD and TIME.
Corsair 550
http://www.corsair.com/_images/charts/vx550w_efficiency.jpg 81% EFF at 100% load. 41A 12v+ = 33.21 – TIME/HEAT = 27.06A GOOD!
However you would not be able to add much of anything else to the system!
The reason I suggested the PC Power and cooling PSU is because it will allow not only the right amount of power, the overhead, quieter but also allow you to use it in the future to add more to your system or to transfer it to a new tower…
PC P&C 610
http://www.pcpower.com/downloads/610_new_5yr%20warranty_lr_3825.pdfThis unit has better components than the Corsair and will run cooler @ 100% load (less or NO heat loss) estimate perhaps 1-2% for heat MAX and their electronic design means only a 5% loss over time for a total of 7% less than the Efficiency Rating.
+12V @ 49A - 83% EFF = 40.67A (minus) TIME/HEAT = 37.24A EXCELLENT!
That UNIT is Premium.. it will run that rig and then some.. you probably wont even hear the PSU running
You get what you pay for if you know how to look for it.. The PC Power and Cooling PSU is the best deal for the price.
With PCP&C
You get 90.9% MORE PSU than the Pixxo 580
You get 37.6% MORE PSU than the Corsair 550 (even though it is a single rail)
You GET what you pay for
If you go with that cheap Pixxo PSU you will be sorry.. perhaps not right away but within a year, no doubt about it.
Thanks
Nick
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