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PSU w/ 18A on 12V rail for GTX 650?

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January 21, 2013 2:05:01 AM

Hello, I am currently working on putting together my first build, and need some help verifying that my existing PSU is ok for what i want to do.

Essentially, I just want to build a modest machine which will mostly be used for internet, but there will be some editing of home HD movies and some gaming.

My current system is an ACER E650 with pentium D. Definitely overdue for an upgrade.

The case, DVD/CD-RW combo drive, DVD drive, and memory card reader will be reused.

I already had to replace the PSU on this machine and hope to reuse it too. It is an ULTRA LS350. Details listed at the link below...

http://www.tigerdirect.com/applications/SearchTools/ite...


The new items are:

MSI H77MA-G43 motherboard
Intel i5 3470 CPU
Kingston HyperX 1600 DDR3 2x4GB RAM
Crucial 64GB SSD
WD Caviar Blue 500GB HDD
MSI GTX 650 GPU

(Just a note on the GPU, Im kinda loyal to NVidia and will only be gaming at 1368x766. Based on that resolution and my power constraints, I'm sure this card is good enough for my needs.)

As for the power supply. I am convinced it is a quality unit. It has lots of features that this forum says to look for (over voltage protection etc... and the stated wattage makes sense). However, it is only rated for 18A on the 12V rail.

NVidia recommends 20A on the 12V rail to use the GTX 650, but I am having a hard time seeing how this build requires that demand.

The i5 3470 is rated at 77w and the GTX 650 at 64w. Roughly speaking, this will be a 13A draw on the 12V rail.

Will the rest of my components really add up to another 5A (60w)?

I know the simple answer is just upgrade the PSU anyways since its the heart of any machine. But 1), I feel i already have a quality unit, its just rated for low wattage. and 2) If i upgrade the PSU, ill also be tempted to spring for a bigger and badder GPU, and i am just not interested in adding another $100 or so to this build.

Also, should be clear from my build, i am not an overclocker.

Thanks in advance for the advice.
a c 667 ) Power supply
January 21, 2013 2:13:14 AM

Well it calls for 400 total watts as well, it might work but we are talking low quality cheap PSU here that might blow up when overstressed.
January 21, 2013 2:25:31 AM

rolli59 said:
Well it calls for 400 total watts as well, it might work but we are talking low quality cheap PSU here that might blow up when overstressed.



Thank you for the reply, but i do have a couple questions...

1) What makes this a low quality, cheap PSU? I know it doesn't say Corsair on Antec on it, but everything else seems to add up ok in my mind. And it sells for $35. That's basically what the Corsair CX430 sells for.

2) Will i be stressing the PSU with my build? Thats kind of what I'm asking with this thread. Maybe my calculations are off, but i have a hard time seeing this build really approaching the 18A max on the 12V rail. Please set me straight if I am incorrect on that.


Thanks again.
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a b ) Power supply
January 21, 2013 3:02:04 PM

I wouldn't put it in my PC...
January 21, 2013 4:36:50 PM

What determines the standard of quality in a power supply? Efficiency does in my opinion. What efficiency means in power supplies is simple, When you convert AC power (the power in your electrical outlet) to DC power (the power your computer components use) there is a certain amount of loss from converting the electricity such as 25%, Using 25% as the loss example (75% Efficiency Rating) What this means if your computer draws 200 Watts DC power, it has to draw 250 Watts AC power from your electrical outlet because 25% of the power is lost from the conversion (and that lost power turns into heat by the way). If your power supply as a higher efficiency rating and a lower amount of loss such as 87% efficiency and 13 % loss, this can only be accomplished with higher quality parts and therefor a better quality power supply (that makes less heat too!).

My standards, I only use power supplies above 82% efficiency, and I prefer above 87% efficiency (Gold Rated)

* 18A on a 12V means 216 Watts (like you stated), This doesn't mean the power supply can maintain that when it begins to heat up and with a lower efficiency rating (77%) your asking for some problems.

Hope this helps! :D 
a c 1098 ) Power supply
January 21, 2013 6:28:49 PM

My vote goes to the Rosewill CAPSTONE-450. It uses the most modern circuit design and highest +12 Volt continuous current rating of those three.
January 21, 2013 6:31:52 PM

ko888 said:
My vote goes to the Rosewill CAPSTONE-450. It uses the most modern circuit design and highest +12 Volt continuous current rating of those three.


I totally agree with ko888, That is a great pick for a power supply with a nice efficiency rating and solid reviews. Including more then enough power for your setup.
a c 1098 ) Power supply
January 21, 2013 6:35:55 PM

Second choice would be the Seasonic S12II Bronze 430W for its very low electrical noise and ripple.
January 21, 2013 6:46:48 PM

I was leaning towards the Rosewill as being the best pick. However, newegg has a great deal on the Corsair. Should i go with the Rosewill for $60 on amazon or Corsair on Newegg for $20 after coupon and rebates? Or is that more of an indicator that the Corsair just isn't in the same class as the Rosewill?
a c 1098 ) Power supply
January 21, 2013 6:55:18 PM

TURDxSANDWICH said:
I was leaning towards the Rosewill as being the best pick. However, newegg has a great deal on the Corsair. Should i go with the Rosewill for $60 on amazon or Corsair on Newegg for $20 after coupon and rebates? Or is that more of an indicator that the Corsair just isn't in the same class as the Rosewill?

You're comparing PSUs directed at two different markets.

The Rosewill CAPSTONE-450 is directed at the higher end of the market.

The Corsair CX430 is directed at the budget entry level market which is very price sensitive.

The warranty lengths are more of an indicator of how the manufacturer ranks the quality of their PSUs. Five years for the Rosewill CAPSTONE-450 and three years for the Corsair CX430.
January 21, 2013 6:57:06 PM

The Rosewill is in a class of it's own with a 80 PLUS Gold Rating, Go for it on Amazon, just make sure you order it directly from Amazon and not through one of their vendors.
a c 667 ) Power supply
January 22, 2013 1:18:41 AM

Well obviously the Rosewill is the best PSU of the 3 but looking at the price the Corsair will do the job and is much better than your current Ultra. It is really your choice how much money you want to spend.
!