Using +12V only Server PSU for a Desktop Motherboard?

[potatocom]

I received a platinum rated PSU that was used in a slim tower server(i was told it's in good condition), it has the standard 24pin ATX power connector and 12V 8pin connector. This PSU delivers +12V only, some pins(3.3V,5V) from the 24pin ATX connectors are "empty", will it work with standard desktop motherboards?

 

I don't have a spare motherboard to test this, I'm thinking to use this for a new Ryzen APU PC build that without putting in discrete graphics card or SATA drive, in this case, is 3.3V and 5V required to boot and run a modern desktop motherboard?

 

Photo of the PSU :

https://imgur.com/LwumzmG

 

[SupaKomputa]

Quote

 

+ 12V : processor, graphics card, fans and some PCIe expansion cards. It is also the main voltage of the motherboard, although it must go through its own VRMs to regulate it. In general, it is the rail that serves the hardware components with the highest consumption.

+ 5V: mechanical hard drives, optical drives, some PCIe and USB expansion cards. All USB ports on a PC run at 5V, and that includes the peripherals that connect to them.

+ 3.3V: RAM memory and SSDs in M.2 format. Furthermore, all PCIe sockets are also capable of providing + 3.3V.

 

 

[potatocom]

13 minutes ago, SupaKomputa said:

 

I'm aware of RAM requiring 3.3V, but do modern desktop motherboards still get 3.3V directly from PSU? or dekstop motherboards nowadays already mostly get power from 12V and down volt it to other components?

[Guest]

42 minutes ago, potatocom said:

I received a platinum rated PSU that was used in a slim tower server(i was told it's in good condition), it has the standard 24pin ATX power connector and 12V 8pin connector. This PSU delivers +12V only, some pins(3.3V,5V) from the 24pin ATX connectors are "empty", will it work with standard desktop motherboards?

 

I don't have a spare motherboard to test this, I'm thinking to use this for a new Ryzen APU PC build that without putting in discrete graphics card or SATA drive, in that case, is 3.3V and 5V required to boot and run a modern desktop motherboard?

What is the standby voltage of the PSU?

 

[potatocom]

9 minutes ago, jonnyGURU said:

What is the standby voltage of the PSU?

 

 

I'm not sure, here is the only information I got from the PSU description :

+12V, 19A
+12VSB, 2A

 

photo of the PSU :

https://imgur.com/LwumzmG

 

[Guest]

16 minutes ago, potatocom said:

 

I'm not sure, here is the only information I got from the PSU description :

+12V, 19A
+12VSB, 2A

 

photo of the PSU :

https://imgur.com/LwumzmG

 

Then no. Standard ATX12V has a +5VSB. Not a +12VSB.  This PSU is useless.

 

[potatocom]

1 minute ago, jonnyGURU said:

Then no. Standard ATX12V has a +5VSB. Not a +12VSB.  This PSU is useless.

 

 

Thanks Jonny!

[vishesh999]

On 2/23/2021 at 9:57 AM, potatocom said:

I received a platinum rated PSU that was used in a slim tower server(i was told it's in good condition), it has the standard 24pin ATX power connector and 12V 8pin connector. This PSU delivers +12V only, some pins(3.3V,5V) from the 24pin ATX connectors are "empty", will it work with standard desktop motherboards?

 

I don't have a spare motherboard to test this, I'm thinking to use this for a new Ryzen APU PC build that without putting in discrete graphics card or SATA drive, in this case, is 3.3V and 5V required to boot and run a modern desktop motherboard?

 

Photo of the PSU :

https://imgur.com/LwumzmG

 

 

I have the exact same question, however, didn't find a concrete answer.

 

If the PSU outputs only 12v, then how will it power the motherboard / other chipsets / RAM that require 5v, 3.3v or lower? Did you have any luck powering a consumer motherboard with this PSU? 

 

[--SID--]

3 hours ago, vishesh999 said:

If the PSU outputs only 12v, then how will it power the motherboard / other chipsets / RAM that require 5v, 3.3v or lower?

The motherboard converts 12v to 3,3v and 5v. Also there are SATA power connectors on the motherboard

[vishesh999]

7 hours ago, --SID-- said:

The motherboard converts 12v to 3,3v and 5v. Also there are SATA power connectors on the motherboard

 

Is this a standard feature across all motherboard or is it specific to only enterprise / server grade motherboards?

 

For instance, if I were to use Asus B550 Motherboard with ONLY a 12V out PSU, would the motherboard know that there is no 5v output from the PSU automatically convert the voltage according to the requirements of the chipsets / components be it 3.3v or 5v? 

 

I am actively researching this topic:- 

 

[--SID--]

38 minutes ago, vishesh999 said:

Is this a standard feature across all motherboard or is it specific to only enterprise / server grade motherboards?

It's a feature of all 12vO motherboards. Also consumer boards from HP, Lenovo, Dell etc.

 

If you want to use a 12vO PSU with a ATX specified motherboard you have to convert 12v to 3,3 and 5 before the power connection to the board.