Note on Haswell PSU Compatibility

[Glenwing]

With all the stir about Haswell PSU compatibility I think it's important to note that if you have a power supply that doesn't support the low power states of Haswell you can simply disable the C6/C7 states in the BIOS and there will be no compatibility issue, the only difference is your idle power draw will be more along the lines of previous CPUs instead of ultra low power which Haswell is capable of.

 

Thus there is no reason to really make a fuss about this.  All power supplies will be usable with Haswell, just some may require a BIOS setting change.

[FireFox]

Cool, I'll probably get a new PSU if I go with Haswell, may as well start from the ground up.

[Dudenstein]

You sir are a gentleman and a scholar!

[everything count to life]

well said. ;)

[Art Vandelay]

If you have a graphics card in, won't the power draw be high enough for most PSUs to handle it, even with the C6/7 state enabled?

[mgsstar]

Thanks for the info Glenwing! :)

[brownninja97]

I'm going to buy you a waffle.

[Glenwing]

I'm going to buy you a waffle.

 

Aww, thanks  :wub:

[Blackterror25]

This is an official list by Intel

 

http://www.intel.com/reseller/psu_selector/

[KJaboski]

If you have a graphics card in, won't the power draw be high enough for most PSUs to handle it, even with the C6/7 state enabled?

 

Now that is something nobody else thought of before...

[christoi]

Thought I'd also mention this since it's relevant, but a unit isn't necessarily incompatible with the sleep states if it's not said to be supported by the manufacturer either.

 

Contrary to what a lot of sites said, the issue here isn't that the power supplies are unable to supply 0.05A on the 12v rail. Instead, since the other rails can still be powered for USB devices and such you can end up with a large load on the 3.3/5v rails, with only a small load on the 12v. With group regulated designs, this can -in a worst case senario- result in out of spec voltage regulation and even trigger OVP, shutting down the system.

 

This sounds like a problem, except that this only occurs if you have a massive load on the 3.3v and 5v rails (generally 100w+) is where this starts to go out of the specified 5% regulation. That rarely occurs with any system, unless you have tens of phones and such charging simultaneously. To put things into perspective, this is similar to having a PC on hibernate mode with USB devices plugged in and powered - it can be an issue with insane load levels, but it's generally not going to happen. It's something you should worry about IF you are constantly pulling more than 5-10A from the minor rails, but otherwise there's nothing to be concerned about.

 

Of course, if you have a generic no-name unit chances are it's not supported, but you shouldn't be using it for other reasons anyways. ;)

 

If you have a graphics card in, won't the power draw be high enough for most PSUs to handle it, even with the C6/7 state enabled?

 

It's a sleep state, so the graphics card isn't going to be powered anyways (memory modules might be, but that's based off the 3.3v rail). Same goes for everything else that runs off the 12v rail, including fans, HDD motors, etc.

Edit: Nevermind, for some reason I had thought it was a sleep state, not an idle one. In that case I'm not sure myself, though since the BCLK is left at 100mhz it may be possible. It seems like most sites think this power supply 'issue' is more important compared to what the C-states actually do though, so I can't much information about the specifics.

[o0odellero0o]

-

[KaareKanin]

Ok, so the Norwegian HW review site HW.no has collected information on which PSUs will support Haswell.

The article can be found HERE.

Now, I know most of you don't know Norwegian, but you'll recognize the name and models. You'll see that under each manufacturer there's at least one bulleted list. If there's ONE bulleted list, those are supposed to be confirmed with Haswell. If there's TWO bulleted lists under a manufacturer, the first one is the PSUs that are confirmed as working and the second one is assumed to be working, but verification is still lacking.

 

An aditional note is that PSUs with conversion from 12VDC to lower DC voltages will most likely be fine. This is as far as i can gather a normal architecture for high efficiency PSUs. 

[trueno2k]

Hi all this is my first post on this forum and I thought I share my findings regarding this subject ;)

 

I am currently still running a Core2Quad system and have been waiting for haswell to start appearing in the shops here in the UK and I've been wondering whether my Antec TP-650 New PSU is compaible with haswell C6/7 states and came across this link published by Modcrash.com which I thought I like to share as for the current moment has not been mentioned on this forum, so hope this will help some Antec PSU owners rest with ease who were worried that they might not have haswell compatible PSU...

 

http://modcrash.com/antec-psu-intel-haswell-compatibility/#.Ua-U85z4Ijl

 

My 2pence worth done :thumb:

[quan289]

Hi all this is my first post on this forum and I thought I share my findings regarding this subject ;)

 

I am currently still running a Core2Quad system and have been waiting for haswell to start appearing in the shops here in the UK and I've been wondering whether my Antec TP-650 New PSU is compaible with haswell C6/7 states and came across this link published by Modcrash.com which I thought I like to share as for the current moment has not been mentioned on this forum, so hope this will help some Antec PSU owners rest with ease who were worried that they might not have haswell compatible PSU...

 

http://modcrash.com/antec-psu-intel-haswell-compatibility/#.Ua-U85z4Ijl

 

My 2pence worth done :thumb:

 

The Antec Truepower New 650w has a DC-DC secondary, so it will be compatible. You do not need to turn off this power state in the BIOS.

 

Edit: For some reason, I thought you was asking a question... lol

Thanks for the link.

 

For some others:

BeQuiet

Corsair

Enermax

Fractal Design

OCZ/PCP&C

Rosewill

Seasonic (the ones with the haswell ready badge)

 

[FireFox]

What happens if you don't disable the C6/C7 sleep states or whatever they're called and you run it with a normal non-Haswell compatible PSU?

[quan289]

What happens if you don't disable the C6/C7 sleep states or whatever they're called and you run it with a normal non-Haswell compatible PSU?

 

The voltages of the +12v raises and go out of specs, trip the Over Voltage Protection, and causing the system to shut off.

 

That's the theory anyway. Typically, you are going to have loads on the 12v rail from the HDDs, fans, GPUs, etc to make up the low power draw of the low power state, and even then, the load on the 3.3/5v rail likely isn't going to be high enough to cause the 12v to raise that high.

[FireFox]

The voltages of the +12v raises and go out of specs, trip the Over Voltage Protection, and causing the system to shut off.

 

That's the theory anyway. Typically, you are going to have loads on the 12v rail from the HDDs, fans, GPUs, etc to make up the low power draw of the low power state, and even then, the load on the 3.3/5v rail likely isn't going to be high enough to cause the 12v to raise that high.

 

So it won't damage anything?

[mgsstar]

So it won't damage anything?

It might and I would not attempt to run it at those states if your psu doesn't support it.

[FireFox]

It might and I would not attempt to run it at those states if your psu doesn't support it.

 

I'll get a compatible PSU anyway, I was just curious :)

[trueno2k]

Edit: For some reason, I thought you was asking a question... lol

Thanks for the link.

LOL... no problems ;)

 

( on a side note would love to see the thumbsup smiley, where or how can I request this? )

[niwas981]

roger that!  ;)

[ooiman92]

One quick question, what's the difference between this and the other sleep states on previous CPUs? My PC pulls 4 watts while it's sleeping? I have a q9550.

[christoi]

One quick question, what's the difference between this and the other sleep states on previous CPUs? My PC pulls 4 watts while it's sleeping? I have a q9550.

 

The C6/C7 states are actually idle, rather than sleep states. The main difference however is reduced power usage, only requiring 0.6w for the CPU.

[ooiman92]

Okay, so that means I should be fine since it doesn't break while it's sleeping? lol