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I need a new PSU, but what should I buy?

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December 4, 2011 12:34:02 PM

Hi Tom's Forums,

So I need a new PSU for my system because during the Black Friday madness I purchased 2 HD 4890's, but I am not sure what to buy. As of right now I am only using one of the HD 4890's.

The System:

Cpu: Intel Core i5-2500k OCed to 4.3GHz
Cooler: Cooler Mater Hyper 212 Evo
MB: Gigabyte ga-z68x-ud3h-b3 (rev. 1.3)
Memory: Crucial Ballistix sport 8GB (4x2) DDR3 1600
HDD: Western Digital Caviar Black 640GB
Optical: DVD Super Multi
Gpu: Hd 4890 OCed Core: 900MHz Memory: 1000MHz
PCI-Express: TP-LINK wireless adapter
Case: NZXT Gamma
Fans: 3 high speed 80mm

From what I read this setup is using about 300W with on-board graphics and 470-490W with one HD 4890. That kinda scares me because my current PSU, OCZ ModXStream Pro 500W, only carries 432W across its two 12V rails. The strange thing being that the computer is fully operational.

I am asking for help because even though I am fairly sure I need a PSU with 640-680W I am hoping I did the math wrong and don't because the new PSU I want maxes out at 620W. I normally don't second guess myself on these things, but logically the computer should not be running as well as it is and that freaks me out.

The PSU I want to buy is the Antec High Current Gamer Series 620W http://www.newegg.com/Product/Product.aspx?Item=N82E168...

For reference my current PSU's power configuration chart is the first shown after following this link. http://www.ocztechnology.com/images/awards/mxsp_wattage...

In the event that the Antec 620 is not powerful enough what is a good PSU that I could purchase without breaking the bank? I would like to spend less than $75.

More about : psu buy

a b ) Power supply
December 4, 2011 12:46:01 PM

500W is enough for a single HD4890.

600 Watt for 2x HD4890 in CrossFireX.

The Antec High Current Gamer Series 620W should work properly for your CF (I am not sure about your OC).

December 4, 2011 1:26:49 PM

Thanks Jemm, I was also thinking that a 600W PSU should be enough, but not all power sources are created equally. The Antec High Current Gamer Series 620W can carry 576W on its single 48A 12V rail. The problem is that a single HD 4890 can use up to 190W @ 16A when overclocked. I am just as concerned with amperage as wattage and knowing that the crossfire setup could use 32A causes me to worry because I don't know how many amps my system needs. In general I am not very tech savvy when it comes to in's and out's of electric current.
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a c 1108 ) Power supply
December 4, 2011 5:37:20 PM
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For a system running with a single Radeon HD 4890 graphics card a power supply with a combined +12 Volt continuous current rating of 32 Amps or greater and with at least two 6-pin PCI Express supplementary power connectors is recommended.

Your OCZ ModXStream Pro 500W (OCZ500MXSP), with its combined +12 Volt continuous current rating of 36 Amps and with its one 6-pin PCI-E and one 6+2-pin PCI-E Supplementary Power Connectors meets the power and connector requirements. That is why it is currently working.

The only reason you would need to upgrade is if you are planning to add another Radeon HD 4890 for 2-way CrossFireX or if you're planning on replacing your current graphics card with one that consumes more power.
December 6, 2011 8:18:01 AM

Thanks for putting my fears and worries to bed guys.
December 6, 2011 8:18:12 AM

Best answer selected by arespirit.
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