Take the 2-minute tour ×
Super User is a question and answer site for computer enthusiasts and power users. It's 100% free, no registration required.

I have opened up my tower and looked at the power supply case and all the numbers on it. I am very lost.

I want to install a second graphics card into my machine so that I can connect a second monitor to it (the onboard graphics card only has 1 VGA/DVI port), but when I try to install it, my power supply can't handle it (computer won't boot up).

What do I need to consider when getting a new power supply, and where can I find out this information? I have downloaded a piece of software called CPU-Z and that provides me with a lot of information about my computer.

share|improve this question
1  
To get the best answer, add in the make/model of the motherboard and graphics card or the make/model of the PC to your original post. Manufacturer's often include power requirement calculators on their websites so knowing make/model is very helpful. –  Tog Nov 3 '11 at 7:45
    
As a side note, don't skimp on PSUs. Always stick to well-known brands (Antec, Corsair, and Seasonic, to name a few). It's not only the name you're paying for, but the quality and the support. –  happy_soil Nov 3 '11 at 12:09
    
Motherboard: ASUSTeK Computer INC. Model: M3A78-CM Current Graphics: ATI Radeon 3100 Graphics Card I want to install alongside: ATI Radeon X1300 Thanks for suggesting me those calculators guys, but I've checked those out earlier and they have like 50 options for which I don't even know what to put. I'm not even sure what's the number I'm trying to get out of them. By what aspect do I rate power supplies anyway? And thanks, all your help is appreciated :)! –  ExitFailure Nov 4 '11 at 2:35

2 Answers 2

You can try using some software, there are online tools that did what you want:

Thermaltake Power Supply Calculator

eXtreme Power Supply Calculator

share|improve this answer

Basically, what do I need to consider when getting a new power supply

You need to know:

  • Your existing power supply specs - there should be a sticker on the PSU with numbers like ( 400W, 70%, 24A Dual Rail etc).
  • Current computer details ( processor type, number of hard drives/optical drives, presence of a graphics card)
  • Existing Power supply consumption - You can perform a rough estimate using power supply calculators such as the ones posted by Marcx
  • New graphics card power supply consumption - you can know about it this by reading reviews of the graphics card.

So, the new PSU should be off Existing Power Supply Consumption + New GPU consumption (assuming you don't have any existing GPU - if so - this should be the difference of the two) + 10% buffer/reserve capacity. Just in case.

share|improve this answer

Your Answer

 
discard

By posting your answer, you agree to the privacy policy and terms of service.

Not the answer you're looking for? Browse other questions tagged or ask your own question.