Haswell PSU

[iamjsed]

I've seen the latest NCIX video regarding Haswell compatible hardware.  I'm just wondering why is the Seasonic M12II 650w is Haswell certified but the S12II 520w is not.

 

I've read jonnyguru's review of the S12II 520w and I remember reading something that this psu can handle very low loads.

[Glenwing]

http://linustechtips.com/main/topic/18698-note-on-haswell-psu-compatibility/

 

:)

[quan289]

A PSU with a DC-DC secondary will be officially compatible with Haswell, which the S12II/M12II 650w+ has. The S12II/M12II Bronze 430~620w and the units that are based on it does not and is a group regulated design. However, this does not mean that all group-regulated design are not supported, even if it is not officially supported by Intel and the PSU manufacturers. This is because they their testing methodology likely test the PSU in the worse case scenario.

 

Anyways, not all group regulated design are "officially" compatible with Haswell because of they behave in crossload scenarios. Basically, when you have a low load on the +12v rail (in this case, the Haswell power state can allow it to go to 0.05) and the load on the minor rails (3.3v/5v) starts to increase, the voltage on the +12v start to increase as well. The scare is that if the load on the minor rail will high enough during this low power state, the +12v voltages may be out of specs and OVP (over voltage protection) of the PSU set off and may not allow it to go back out of this state and shut down.

 

Here's the thing. If you are on idle and your processor goes into this power state, the fans, HDD, GPU, etc. will still be putting some load on the +12v as well which will balance the load more so this won't happen.

What if you have a passive computer with no fans, HDDs, GPU and such to put some more load on the +12v rail? Unless you have a very poor, old group regulation PSU, it's still highly unlikely that the load of the minor rails will be high enough to negetively affect the voltages in such a way either.

Of course, if you have a crapload of SSDs or something of the sort that will increase your 3.3/5v for whatever reason, then it might cause a problem. But as Glenwing thread post stated, there should be an option in the BIOS on it for you to disable. The only drawback is your idle power draw will be slightly higher.

[CwGoh]

A PSU with a DC-DC secondary will be officially compatible with Haswell, which the S12II/M12II 650w+ has. The S12II/M12II Bronze 430~620w and the units that are based on it does not and is a group regulated design. However, this does not mean that all group-regulated design are not supported, even if it is not officially supported by Intel and the PSU manufacturers. This is because they their testing methodology likely test the PSU in the worse case scenario.

 

Anyways, not all group regulated design are "officially" compatible with Haswell because of they behave in crossload scenarios. Basically, when you have a low load on the +12v rail (in this case, the Haswell power state can allow it to go to 0.05) and the load on the minor rails (3.3v/5v) starts to increase, the voltage on the +12v start to increase as well. The scare is that if the load on the minor rail will high enough during this low power state, the +12v voltages may be out of specs and OVP (over voltage protection) of the PSU set off and may not allow it to go back out of this state and shut down.

 

Here's the thing. If you are on idle and your processor goes into this power state, the fans, HDD, GPU, etc. will still be putting some load on the +12v as well which will balance the load more so this won't happen.

What if you have a passive computer with no fans, HDDs, GPU and such to put some more load on the +12v rail? Unless you have a very poor, old group regulation PSU, it's still highly unlikely that the load of the minor rails will be high enough to negetively affect the voltages in such a way either.

Of course, if you have a crapload of SSDs or something of the sort that will increase your 3.3/5v for whatever reason, then it might cause a problem. But as Glenwing thread post stated, there should be an option in the BIOS on it for you to disable. The only drawback is your idle power draw will be slightly higher.

 

Sorry to dig up an old thread, but so the 550 watt version is okay with Haswell?