connecting two PSUs

[DiamondFX]

I read around and couldn't quite get this idea. People say it's safe but I still don't know how to do it. Here is the 24 pin. Some people say connect the 2nd power supply's ground (black) and green cable to the 1st (primary) power supply and we are good to go. Is this what we need to do exactly to use two different power supplies in the same system? 

 

http://www.overclock.net/t/771029/how-to-connect-a-second-psu-to-power-only-graphics-card

 

[target39]

I read around and couldn't quite get this idea. People say it's safe but I still don't know how to do it. Here is the 24 pin. Some people say connect the 2nd power supply's ground (black) and green cable to the 1st (primary) power supply and we are good to go. Is this what we need to do exactly to use two different power supplies in the same system? 

 

http://www.overclock.net/t/771029/how-to-connect-a-second-psu-to-power-only-graphics-card

Yes, this will work, but I see no reason for you to use two.

[DiamondFX]

Yes, this will work, but I see no reason for you to use two.

 

I am trying to update my friend's rig and we only have 300W and 200W PSUs. We are going to use E2180 dual core, 3gbs of ram, 1 hdd, some fans, a HD 7750 GDDR5 gpu (powered just by the MB - 75W max I think). This is the reason. He couldn't find 500W psu and we wanna try this. Would this technique power on the 2nd power supply? Do I need to connect the power cable to the second power supply? (Stupid question I know) * Never tried it. 

 

My plan is this: 

 

300W connections for :

4 pin and 24 pin connections to the MB. (CPU+MB+GPU) 

 

200W

DVD

HDD

FANS

[target39]

I am trying to update my friend's rig and we only have 300W and 200W PSUs. We are going to use E2180 dual core, 3gbs of ram, 1 hdd, some fans, a HD 7750 GDDR5 gpu (powered just by the MB - 75W max I think). This is the reason. He couldn't find 500W psu and we wanna try this. Would this technique power on the 2nd power supply? Do I need to connect the power cable to the second power supply? (Stupid question I know) * Never tried it. 

 

My plan is this: 

 

300W connections for :

4 pin and 24 pin connections to the MB. (CPU+MB+GPU) 

 

200W

DVD

HDD

FANS

You don't need 500w to power this system. Try powering the whole system only with the 300w PSU. It should be able to run.

[quan289]

Both power supplies need to be plug in. The second one needs to be getting power some somewhere afterall.

 

It is also not recommended to used two random PSUs together, as it may not be design to handle particular loads - particularly PSUs that are group-regulated where the 5v and 12v shared the same regulation mechanism. What happen is that when you put some load on one rail, it will affect the voltages of the other. "Load imbalances" on an irregular setup may cause stability issues due to poor regulation.

 

Your friend's system isn't particularly demanding, so a 300w can handle a Pentium dual-core and a GPU that doesn't draw more than 55w DC.

[DiamondFX]

You don't need 500w to power this system. Try powering the whole system only with the 300w PSU. It should be able to run.

 

You're right actually. It should run. I am just worried it might peak around 300W and the PSU might not be enough. The Cooler Master site says 250W max. Should I test the system with just 300W and like run MSI Kombustor for a full stress test? 

 

http://www.coolermaster.outervision.com/PSUEngine

 

[DiamondFX]

Both power supplies need to be plug in. The second one needs to be getting power some somewhere afterall.

 

It is also not recommended to used two random PSUs together, as it may not be design to handle particular loads - particularly PSUs that are group-regulated where the 5v and 12v shared the same regulation mechanism. What happen is that when you put some load on one rail, it will affect the voltages of the other. "Load imbalances" on an irregular setup may cause stability issues due to poor regulation.

 

Your friend's system isn't particularly demanding, so a 300w can handle a Pentium dual-core and a GPU that doesn't draw more than 55w DC.

 

 

 

 

Thanks for the info quan289, I'll just use the 300W then.