Can I connect two 12v rails on a PC power supply?

AI Thread Summary
Connecting two 12V rails from a dual-rail power supply to power a 320W TEC is feasible as long as both rails share a common ground. However, caution is advised due to potential stability issues and output voltage discrepancies between the two rails, which can lead to oscillations or insufficient current supply. While some users have successfully paralleled power supplies, it generally requires additional circuit features for reliable operation. The discussion highlights the difficulty of paralleling power supplies and the importance of ensuring proper voltage levels. Overall, using a dual-rail power supply for this application is a practical solution if the necessary precautions are taken.
GeordiLaForge
Messages
3
Reaction score
0
I just bought a 320w TEC to cool my processor. But the problem is, I can't afford a power supply that can provide enough amps through a single 12v rail. If I buy a power supply that has dual 12v rails, can I wire them together in order to provide enough amps to the TEC? I won't have anything else hooked to this power supply, only the TEC. Thanks in advance for the help!
 
Engineering news on Phys.org
Yes, as long as they share the same ground, which they should.
 
waht said:
Yes, as long as they share the same ground, which they should.
THANK YOU SO MUCH! I've been trying to get an answer to that for 2 days on various PC forums... That made my day! Decent power supplies with a single 12v rail are hard to come by nowadays. And I wasn't willing to pay over $200 for a PSU with strong enough rails. Thanks again for your help!
 
GeordiLaForge said:
I just bought a 320w TEC to cool my processor. But the problem is, I can't afford a power supply that can provide enough amps through a single 12v rail. If I buy a power supply that has dual 12v rails, can I wire them together in order to provide enough amps to the TEC? I won't have anything else hooked to this power supply, only the TEC. Thanks in advance for the help!

I have to disagree with waht on this one. You might be able to parallel the two power supplies to increase the overall output current, but in general that may not work.

There are two potential issues -- stability and output voltage. Stability can be a problem because you will have two separate switching power supply loops that are both trying to stabilize the output voltage, and they can talk to each other and cause oscillations or even worse, overvoltages.

The second problem is that each of the two power supplies can only pull the output rail up, and will only pull up (supply output current) if they see that the rail is at or below the output voltage that they are trying to get to. So if one supply's output voltage stand-alone is 12.1V, and the other is 11.9V, then the 2nd power supply will not supply much current into the output as long as the 12.1V power supply is connected to its output.

Paralleling power supplies in the general case is a pretty difficult problem, and requires some extra circuit features to make it work reliably.
 
I agree with Berkman, but I'm actually confused more about the original question, the rail thing.

I'm aware a PC power supply taps the voltage from the transorfmer. More power means you need a more powerful transformer. In regular power supplies, a 12V is tapped from one winding providing the necessary current.

Is this what you call a single rail? This way all 12V outputs (usually the yellow cable) can be hooked up to anything.

Now the dual power supplies, for high performence PCs have two independent 12V taps from main transformer, making it more stable because it's easier to stabilize two lesser power outputs.

I think this is what you refer to is dual rail?

But even in this, the two indepentent 12 V output have to be phased locked anyway since this is a switching power supply, so you could use either rail whenever you want provided the power supply can supply enough amps.

But if you want to hook up two different PC power supplies together, single rail then you might ran into problems berkman explained. But if the other power supply is powering a fan that would no problem.

Hope that helps.
 
I'll be connecting two 12v rails off of one power supply with dual 12v rails. It has overvoltage protection, and they do in fact share a ground, so I'm confident that it'll work. Thanks for your help!
 
Hi all I have some confusion about piezoelectrical sensors combination. If i have three acoustic piezoelectrical sensors (with same receive sensitivity in dB ref V/1uPa) placed at specific distance, these sensors receive acoustic signal from a sound source placed at far field distance (Plane Wave) and from broadside. I receive output of these sensors through individual preamplifiers, add them through hardware like summer circuit adder or in software after digitization and in this way got an...
I have recently moved into a new (rather ancient) house and had a few trips of my Residual Current breaker. I dug out my old Socket tester which tell me the three pins are correct. But then the Red warning light tells me my socket(s) fail the loop test. I never had this before but my last house had an overhead supply with no Earth from the company. The tester said "get this checked" and the man said the (high but not ridiculous) earth resistance was acceptable. I stuck a new copper earth...
Thread 'Beauty of old electrical and measuring things, etc.'
Even as a kid, I saw beauty in old devices. That made me want to understand how they worked. I had lots of old things that I keep and now reviving. Old things need to work to see the beauty. Here's what I've done so far. Two views of the gadgets shelves and my small work space: Here's a close up look at the meters, gauges and other measuring things: This is what I think of as surface-mount electrical components and wiring. The components are very old and shows how...
Back
Top