Double PSU possible?/ or stick to one?(gpu upgrade)(new issue)

JelleS

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Jul 16, 2013
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Setup:
CPU: Intel i5-2500 3.3 MHz
PSU: 240 W built-in (high efficient)
RAM: 4 GB DDR3
GPU(Current: Nvidia GeForce 9500 GT)
GPU: New-Asus HD 7790 1 GB DDR5 (http://tweakers.net/pricewatch/330230/asus-hd7790-dc2oc-1gd5/specificaties/)

I'm not sure if the power can handle the GPU upgrade, and the pc is too small for an psu upgrade, so I thought it might be possible to use another PSU outside of the pc for the GPU only. I'm not sure if this is possible/safe, what are your thoughts of this?
 

Tobmaster

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Jul 16, 2013
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That is absolutely possible, but will be kind of ugly with a standard PSU sitting next to your PC. (a few years back, I actually saw power bricks made to run a GPU). If possible, get a bigger case and PSU to match your needs and you'll be much happier
 
And The correct answer is - Yes but probably not recommended.
1) Primarily a +12V issue. You can use daul Power sources PROVIDING NONE of the +12V positive rail from PSU 1 are shorted to a +12 V positive rail on PSU 2. Returns (Ground) will be shorted. Ie if You use PSU 2 to provide +12 to GPU via the 6 pin power connector, then you would need to verify that the +12 v pci-e connector on GPU does NOT connect to the PCI-e bus +12V on GPU Card (Should be issolated, but should verify). HDD/CD-DVD drive should be no problem.
2) The 2nd PSU would have NO load on any of the Other rails. +5 would have a small load if connecting to a Hard drive and or DVD drive. But for example the 3.3 V = No Load. Some switching PSs do NOT like a NO load condition.

Bottom Line - concur with Ram1009, New case and PSU (recommend a quality 450 W as a Min). Needs a 6 pin Power connector.

While your PSU may handle the card, it is too close to possible max power consumption. Also "250 watt high eff" does not provide the full picture as it does not indicate the +12 V rail output. The Majority of your power will be derived from the +12V rail (ie the CPU and the GPU).

Some references:
.. Do not forget you need 6 pin PCI-e GPU power connector
.. System power – Max just over 250 Watts (Your system will be lower, maybe as low as 200 Watts, But this is just a little too close to 250W and does not address my previous concern on +12V power)
http://www.newegg.com/Product/Product.aspx?Item=N82E16814121727&nm_mc=KNC-GoogleAdwords&cm_mmc=KNC-GoogleAdwords-_-pla-_-Desktop+Graphics+Cards-_-N82E16814121727&gclid=CIP_hsertLgCFUxgMgodfiQACQ
The Gpu itself – max power just over 100 Watts
http://www.anandtech.com/show/6837/amd-radeon-7790-review-feat-sapphire-the-first-desktop-sea-islands/16
 

JelleS

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Jul 16, 2013
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I have decided to put my sff6200 (specs from first post, new gpu is gtx 650 ti boost) INSIDE my old case(much bigger) which leaves enough space to put a 450w power supply for ONLY the 6pin for my new gtx 650 ti boost graphics card.

Is this going to work? Or is the gtx 650 ti boost going to use all the power from the motherboard of the other power supply (230w) which will cause it to crash probably or does it perfectly balances it so it uses most of the power of the 450w power supply?