Concept HDPlex 400w + TWO dell 240w power bricks in Parallel ?

[marcosopeth]

Hello!

I'm thinking of building a Mini ITX project with a HDPlex 400w.

Has anyone thought of feeding the system with two power bricks instead of one ? ( I mean in parallel connection).

I have seen many projects with Dell 330w adaptor + HDplex 400w and this system often does not provide enough power.

Using two 240w adaptors in parallel and considering an efficiency of perhaps 85%, we would have a power of approximately 410 W.

It would be a perfect feed for a 400w HDplex.

Of course this would be an alternative to the existing 400w AC / DC power supply.

Thoughts?

 

[Jello]

What kind of build are you planning on powering with this?

 

[Windfall]

Hello!

I'm thinking of building a Mini ITX project with a HDPlex 400w.

Has anyone thought of feeding the system with two power bricks instead of one ? ( I mean in parallel connection).

I have seen many projects with Dell 330w adaptor + HDplex 400w and this system often does not provide enough power.

Using two 240w adaptors in parallel and considering an efficiency of perhaps 85%, we would have a power of approximately 410 W.

It would be a perfect feed for a 400w HDplex.

Of course this would be an alternative to the existing 400w AC / DC power supply.

Thoughts?

This MIGHT be powerful enough, but I don't feel like doing the math.

http://www.mini-box.com/Y-PWR-Hot-Swap-Load-Sharing-Controller

 

[Thehack]

Hello!

I'm thinking of building a Mini ITX project with a HDPlex 400w.

Has anyone thought of feeding the system with two power bricks instead of one ? ( I mean in parallel connection).

I have seen many projects with Dell 330w adaptor + HDplex 400w and this system often does not provide enough power.

Using two 240w adaptors in parallel and considering an efficiency of perhaps 85%, we would have a power of approximately 410 W.

It would be a perfect feed for a 400w HDplex.

Of course this would be an alternative to the existing 400w AC / DC power supply.

Thoughts?

You cannot use parallel DC convertors unless they specifically support parallel connections.

Slight voltage difference will cause unwanted current flow.

Also, one powerful brick should be smaller than two less powerful ones.

 

[Windfall]

You cannot use parallel DC convertors unless they specifically support parallel connections.

Slight voltage difference will cause unwanted current flow.

Also, one powerful brick should be smaller than two less powerful ones.

Won't the pico-box y-pwr do it?

 

[Choidebu]

Won't the pico-box y-pwr do it?

Yes, but with a catch: that Y-pwr is first and foremost meant to be used for redundancy; which means it'll switch the load to the supply with higher voltage, as with its intended purpose to provide fail over. if you use it with two brick in theory it'll switch between the two whenever one's voltage drops (which happens when on load). But this means if you do use more load than either supply, the supply with stronger regulation will bear its full rated power, basically running 100% most of the time while the other just bear the rest. Over time, you can guess what happens...

 

[aquelito]

You cannot use parallel DC convertors unless they specifically support parallel connections.

Slight voltage difference will cause unwanted current flow.

Also, one powerful brick should be smaller than two less powerful ones.

One 240W for the system, one 240W for the GPU using a riser with +12V tracks cut should solve that issue right ?

 

[Thehack]

One 240W for the system, one 240W for the GPU using a riser with +12V tracks cut should solve that issue right ?

Yes and no. That works, but is not good practice. In a multi rail psu, which we used to have more back in the day, the rails talk to each other to keep the voltage close and have safeguards against reverse current flow.

Generally the power gets used closest to load device. But nowadays, with single rail being prevalent, you don't know how the motherboard and GPU would interact with two rails that don't communicate.

 

[aquelito]

If the GPU is completely isolated from the motherboard, how could they communicate ?

 

[Thehack]

If the GPU is completely isolated from the motherboard, how could they communicate ?

If we're talking about power rail, the psu internal controller detects voltage differences and corrects it. This is what generally happens in a multi rail power supply.

It is possible on the component the PCIe 12V and Mobo 12V to be complete isolated from each other, but it is still bad practice. The ground potential may be different as well.

You can see this when you use a 12V or other output (like a fan) from the motherboard to trigger a mosfet to supply power to the gpu. The 12V rail was actually connected, so that when the GPUs power was supposed to be turned off, the capacitance kept the 12V on, kept then feedback on loop of supplying power to the motherboard.

 

[Choidebu]

I think you nailed this with 'possibility of differing ground potential', @Thehack .

This is always what worries me the most about using two supplies, not so much with two same model, but still. If I ever tried these setup I'll be setting up a volt meter between those two ground planes.

 

[Windfall]

If we're talking about power rail, the psu internal controller detects voltage differences and corrects it. This is what generally happens in a multi rail power supply.

It is possible on the component the PCIe 12V and Mobo 12V to be complete isolated from each other, but it is still bad practice. The ground potential may be different as well.

You can see this when you use a 12V or other output (like a fan) from the motherboard to trigger a mosfet to supply power to the gpu. The 12V rail was actually connected, so that when the GPUs power was supposed to be turned off, the capacitance kept the 12V on, kept then feedback on loop of supplying power to the motherboard.

A bit off topic, but I'm super thankful for your expertise in power delivery. Without you, this forum would not be what it is now!