Which GPU's can I run with this PSU?

Jdogdemapples

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Mar 13, 2013
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I recently have had the opportunity to upgrade my graphics card through my friend's employee discount (works at PNY) and I could get GPU's for pretty much dirt cheap. My PCU isn't great, but its not worth upgrading considering that I would probably put more into the PCU than the GPU itself.

My PCU is 550 watt, has two 12v rails - one at 28 amps and the other at 20amps - and is +80 bronze.

Here is a link for all of the information:
http://hecgroupusa.com/home/hec550tb/

Currently I am running a GTX 550 Ti that is overclocked. I have no problems whatsoever with the PSU. The 550 Ti has a TPD of 116 watts and 9.7 amps.

Here are some GPU's I can get:

GTX 660 Ti - 150 watts and 12.5 amps
GTX 670 - 170 watts and 14.2 amps
GTX 770 - 230 watts and 19.2 amps
GTX 780 - 250 watts and 20.8 amps

Note that all power ratings are based on the card's TPD and that I have no intention to overclock or reach the TPD with the new card.

So my questions are:
1. Which card should I get? (I am looking for the best card that my PSU can safely handle)
2. Do I have to worry about the dual rails? If so, how do I wire the GPU to ensure that it is receiving enough power?
3. Some of the cards require 8 pin connectors. Can I buy a converter to convert 6 pin to 8 pin and does it matter which of the two 6 pins I convert?
4. I also have no idea how to tell which wires are on which rails so I don't know if I would be wiring it correctly of not.

Last note: I am running a i7 2600 CPU w/ 10% OC, 8 gb RAM, 1TB HD, Blu Ray, 2 case fans, 1 CPU fan, motherboard, and wired keyboard and mouse. I would estimate that it draws about 220 watts at full load.

Thank you for reading.
 

ayushde

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Feb 6, 2013
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I think you wont be able to run anything more than a 660ti. Try and get the 660 ti
 

Jdogdemapples

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Mar 13, 2013
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I don't really understand why I'm limited though, I mean there are 40 amps that my PSU can provide on the 12v rail, yet I cannot select a card that can utilize the amperage?
 

ayushde

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Feb 6, 2013
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The wattage of your psu is too less to run anything over a 660ti.
 

sourodip

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it's not always the amps(current)it can deliver but also the wattage,get the gtx660Ti,it would be the best choice for ur psu and if want to get something better like gtx770 or hd7970,then buy a new psu
 

sourodip

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yeah psu needs to be upgraded(if u do not have one really good)) for a high-end gpu bcoz. the psu provides the power to the gpu and the whole system and if if u does not give the recommended wattage psu to the psu,u would be under huge risk.
ex-for saving 30$ on a psu and getting a cheap one could damage your 200$ gpu