bit-tech.net

Haswell C states raise PSU compatibility fears

Haswell C states raise PSU compatibility fears

Enermax has stated that its high-end power supplies are ready for Haswell, but other manufacturers are slow to address compatibility concerns surrounding the new chip's C states.

New power efficiency features in Intel's upcoming Haswell processors, due to launch in June at the Computex event in Taipei, could mean they fail to work correctly with certain power supplies, it has been claimed.

Intel has made much about the low-power capabilities of Haswell, the architecture on which its upcoming fourth-generation Core processors are based - even claiming that Haswell-based laptops will be able to spend up to ten days in an internet-connected semi-standby mode from a single charge. Much of this efficiency comes from new processor states, C6 and C7, which drop the power consumption of a sleeping Haswell processor to a tenth that of its Ivy Bridge predecessors.

There's a problem, though: not all power supplies are designed to cope with running at such low current. For original equipment manufacturers (OEMs) building laptops, that's not a problem: they can just specify power supply circuitry happy running at very low loads. For enthusiasts hoping to upgrade existing Ivy Bridge or Sandy Bridge desktops to Haswell, however, it's bad news.

'Only few power supplies will be able to deliver stable voltages at such low loads,' claims Enermax, one of the few power supply companies to talk publicly on the issue. 'End users are therefore groping in the dark with no clues if their own power supply will be compatible with the new energy functions of Intel Haswell CPUs. PSU manufacturers usually do not state the possible minimum load of their products.'

The fact that Enermax is willing to highlight the problem should give you a hint as to what comes next: the company, which claims to be 'one of the technologically leading power supply manufacturers' in its press release on the matter, is looking to reassure its customers that as long as they have an Enermax power supply, they should be right as rain for a Haswell upgrade. 'All current high-end and mid-range models from Enermax are already prepared for the upcoming Intel processors,' the company claims. 'They are equipped with a DC-to-DC converter which enables the so-called ZERO Load Design. These power supplies will deliver rock-stable voltages even at 0W load.'

That design, which allows the power supply to operate correctly even when there is no current being demanded by the system, is something the company adopted back in 2008 with the launch of the Revolution85+, and has been using in its top-end models ever since. Not all Enermax power supplies get the required DC-to-DC circuitry, however: the Platimax 500W, 600W, 750W, 850W, 1000W, 1200W and 1500W models, Revolution 87+ 550W, 650W, 750W, 850W and 1000W, MaxRevo 1200W, 1350W, 1500W and Triathlor 385W, 450W and 550W all include the circuitry as standard, but other current Enermax PSUs do not - and thus are unlikely to be compatible with Haswell.

So far, no other manufacturers have publicly commented on the issue, which was first raised by VR-Zone late last week. It seems likely, however, that motherboard manufacturers will disable the new C6 and C7 states by default - circumventing the problem - rather than face support calls from angry customers wondering why their new motherboard and processor combination is failing to work on a known-good power supply.

For those who actively want the energy saving features of Haswell - something which is less important in a desktop than a laptop, despite rising energy costs - the message is clear: if you're building a new rig, choose your power supply carefully; if you're upgrading, budget for a new PSU just in case.

25 Comments

Discuss in the forums Reply
Stanley Tweedle 1st May 2013, 10:56 Quote
I got an enermax Modu 82+ and I dung really care if it has the zero load bla bla cos unless the cpu is unlocked and overclocks well and gives significant advantage over i5 2500k then I wunt be bothering.
damien c 1st May 2013, 11:27 Quote
I will be fine with my Coolermaster PSU, since I am not buying a Haswell CPU after just last month going to SB-E.

I will however be keeping a eye on this for the pc's that I will build people using a Haswell CPU, and it's good to know Enermax will be ok to use, although I have never used one myself previously.
rollo 1st May 2013, 11:53 Quote
Surprised this has just come out now in all honesty. Most older psus 3-4 years will not be compatible so people on the older x58 and below ( the most likely upgraders in enthusaist market) will likely need a new psu if they want these power savings.

Its a cost that most will not have budgeted for as a decent 750-850 watt psu is easily £100 makes haswell not a very tempting upgrade unless its awesome.

£260 4770k
£150 SLI mobo ( cheap mobos dont do sli )
£125 PSU ( seasonic x 750 watt )
8 - 16 gb ram price is £50 for 8gb £100 for 16gb at the moment

Total haswell upgrade price has just hit a cool £585 - £635 if you want all its features and are on a older psu and need new memory modules.

socket 2011 is only about £100 more for what will be a much faster 6 core cpu and a better mobo to boot.

3930k is £463, Mobo call it £200 16gb ram is £100 now a days ( ram prices are rising fast again )

Wonder how many people will buy it then relise they cant do most of these power savings as the psu is not compatible.
Instagib 1st May 2013, 12:39 Quote
Surely getting a decent platinum or gold rated psu would be a better energy saving if you're all that bothered? That way, there is better efficiency when you are actually using the rig, and then when you are not, turn it off at the socket....
Omnituens 1st May 2013, 13:30 Quote
Can't you just disable the states in the BIOS? If not, :(

I was thinking of moving to Haswell as I am currently on a i7 920 and it's starting to show its age. But if I have to get a new PSU as well... :(
edzieba 1st May 2013, 13:37 Quote
Quote:
Originally Posted by Omnituens
Can't you just disable the states in the BIOS?
Yes, you can. ALL you lose from having an 'incompatible' PSU is that the idle state consumes a few watts (i.e. still less than current processors) rather than half a watt.
Gareth Halfacree 1st May 2013, 14:31 Quote
Quote:
Originally Posted by Omnituens
Can't you just disable the states in the BIOS? If not, :(
Quote:
Originally Posted by The Article
It seems likely, however, that motherboard manufacturers will disable the new C6 and C7 states by default - circumventing the problem - rather than face support calls from angry customers wondering why their new motherboard and processor combination is failing to work on a known-good power supply.
r3loaded 1st May 2013, 14:33 Quote
What's the exact issue that would occur with an incompatible PSU and the C6/C7 states? Will it fail and cut power to the system, or just supply power inefficiently, churning through like 10-20W while supplying 2W to the system?
Gareth Halfacree 1st May 2013, 14:54 Quote
Quote:
Originally Posted by r3loaded
What's the exact issue that would occur with an incompatible PSU and the C6/C7 states? Will it fail and cut power to the system, or just supply power inefficiently, churning through like 10-20W while supplying 2W to the system?
While it's possible some PSUs would turn themselves off at low draw, the bigger problem is voltage ripple: without enough load on the rails, the PSU is likely to start flailing around and pumping too much voltage in one place and too little in another. Electronics don't like that very much, and while it's unlikely the ripple would be bad enough to break anything - the +12V rail isn't going to start giving 240V, for example - it would be enough to confuse the system and corrupt the contents of memory.

Basically, if you disable the C6/C7 sleep states you should be fine - but you'll be missing out on one of the new features brought about by Haswell. Like I say in the article, though, it's a bigger problem for battery-powered devices.
coyote 1st May 2013, 18:04 Quote
I guess using less power is a good thing, but having to buy a new PSU as well to take advantage of it! That's almost like Intel shooting themselves in the foot. I don't think I'll be upgrading to Haswell any time soon.
Bloody_Pete 2nd May 2013, 07:47 Quote
Wait, so although my Revolution 85+ has the DC-DC converter its not supported...?
Gareth Halfacree 2nd May 2013, 07:58 Quote
Quote:
Originally Posted by Bloody_Pete
Wait, so although my Revolution 85+ has the DC-DC converter its not supported...?
No, your Revolution 85+ will (should?) be fine: Enermax has, for obvious reasons, only provided a list of current PSUs which it states are compatible. 'Cos, y'know, they want people to buy a new PSU.
ch424 2nd May 2013, 08:13 Quote
Quote:
Originally Posted by Gareth Halfacree
While it's possible some PSUs would turn themselves off at low draw

I've already had this problem on my system - I've got a CX380 and it wouldn't boot my APU system because it didn't draw enough current. I had to plug three fans in just to trick it into working!

How long until we see firmware updates for PSUs to fix this sort of thing?
Phil Rhodes 2nd May 2013, 10:52 Quote
Annoying. I just bought a decent Corsair power supply. I have an 8-disk RAID10 in the same box; might that be enough of a buffer load, or are they concerned about the 3.3V line?
Anfield 2nd May 2013, 16:10 Quote
Quote:
Originally Posted by Phil Rhodes
Annoying. I just bought a decent Corsair power supply. I have an 8-disk RAID10 in the same box; might that be enough of a buffer load, or are they concerned about the 3.3V line?

Its about the 12V2 exclusively used by the Cpu and nothing else, so no, other HW won't help you get over the minimum, according to here you may be fine with a Corsair Psu:
Quote:

However, the PSU selector on Intel's Reseller Center website includes a list of power supplies, and that list can be sorted by support for a minimum 12V2 load of 0 amps. I count only 23 units with that capability: 19 Corsair models, three InWin units, and a single Seasonic.
ffjason 2nd May 2013, 18:42 Quote
Quote:
Originally Posted by ch424
I've already had this problem on my system - I've got a CX380 and it wouldn't boot my APU system because it didn't draw enough current. I had to plug three fans in just to trick it into working!

How long until we see firmware updates for PSUs to fix this sort of thing?

PSU's don't have "firmware". You will not get a firmware update for your PSU unfortunately.
ch424 2nd May 2013, 19:21 Quote
Quote:
Originally Posted by ffjason
PSU's don't have "firmware". You will not get a firmware update for your PSU unfortunately.

I meant that in the future (a few years?) they might have a microcontroller driving them because it'd be simpler/cheaper than having several power management ICs.
fluxtatic 3rd May 2013, 06:55 Quote
Not really seeing this as an issue as far as desktop PSUs go. While it would be a novel idea, especially the connected-sleep sort of deal, your average enthusiast isn't going to much care about the difference between .5W and 4W.

At least in the Windows world, my experience with sleeping a PC has never been all that great anyway. It's Windows - you either leave it running always and reboot when it starts getting flaky, or shut it down every night so it doesn't get flaky (and chew up your power bill, to boot.)

I'd be surprised if the major PSU OEMs and ODMs weren't already aware of the issue and will have it addressed by the time Haswell has actually dropped (for those that haven't already handled it, like Enermax.)

All in all, from what I've heard so far, Haswell is a bit less exciting than I'd expected, from a practical standpoint. From the engineering, super hardcore nerd point of view, it's exciting with the new arch and all. But it's definitely diminishing returns - if you aren't a bleeding-edger and you're at least on SB, doesn't seem worth the cash. I'll reserve judgment until benchmarks start coming out, but it seems less exciting than it did at first blush, all those months ago, at least in desktop-land.
r3loaded 3rd May 2013, 10:31 Quote
Quote:
Originally Posted by fluxtatic
All in all, from what I've heard so far, Haswell is a bit less exciting than I'd expected, from a practical standpoint. From the engineering, super hardcore nerd point of view, it's exciting with the new arch and all. But it's definitely diminishing returns - if you aren't a bleeding-edger and you're at least on SB, doesn't seem worth the cash. I'll reserve judgment until benchmarks start coming out, but it seems less exciting than it did at first blush, all those months ago, at least in desktop-land.
It's not meant to be exciting for desktops! It's meant to be exciting for mobile devices - tablets and laptops with Haswell chips will get better battery life, massively better iGPUs and other hardware-level features like Connected Standby which should allow Haswell devices to sleep like phones, saving power while staying connected. Intel are focusing almost exclusively on mobile because that's exactly where the money is!

We desktop enthusiasts (or even just desktop owners) are fading away nowadays - the vast majority of people don't need a desktop at all now. Heck, if I didn't game a lot or run stuff like folding/litecoin mining, my needs would be served almost completely by the 15 inch retina MBP.
faugusztin 3rd May 2013, 10:43 Quote
Quote:
Originally Posted by Anfield
Its about the 12V2 exclusively used by the Cpu and nothing else, so no, other HW won't help you get over the minimum, according to here you may be fine with a Corsair Psu:

That listing is as useless as much is possible for a list to be useless. For example Seasonic - you got X series PSU ? Sorry, they won't list those. XFX ? What ? XFX makes power supplies ? Not according to that list.

In short, that list covers only very small part of the PSU market and for that reason it is useless to check this problem. Especially if the only informations it has on 12V2 line is yes or N/A (aka "we don't know").
Anfield 3rd May 2013, 13:10 Quote
Quote:
Originally Posted by faugusztin
That listing is as useless as much is possible for a list to be useless.

The guy who I posted it in reply to was specifically referring to his recently purchased Corsair psu (and they are listed), as was I.

I have never claimed the list top be complete or useful in general.
faugusztin 3rd May 2013, 13:36 Quote
Quote:
Originally Posted by Anfield
The guy who I posted it in reply to was specifically referring to his recently purchased Corsair psu (and they are listed), as was I.

I have never claimed the list top be complete or useful in general.

Which doesn't mean anything considering Corsair doesn't make their own PSU, and his model (btw there is no such thing as CX380) can be made by anyone (Seasonic ? Flextronics ? CWT ?)

Unless you got exactly the same model listed on that site and it says Yes for exactly that model, then that list is completely useless. N/A doesn't mean No, and not being listed doesn't mean anything either.

In short, all that list does is providing confirmation for few PSU who has "yes" in that column, every other PSU (listed or unlisted) can be OK or incompatible.

And that is why that list is completely useless. It is completely useless for ch424 as well and with big chance it is useless for Phil Rhodes too.
ch424 4th May 2013, 14:14 Quote
Quote:
Originally Posted by faugusztin
(btw there is no such thing as CX380)

Yeah, sorry - I meant the CX 430W. Not sure where I got 380!
MSHunter 6th May 2013, 09:13 Quote
If you can do USB charging when PC is off would that suggest that your PSU might work?
Gareth Halfacree 6th May 2013, 10:52 Quote
Quote:
Originally Posted by MSHunter
If you can do USB charging when PC is off would that suggest that your PSU might work?
Not necessarily: the USB port uses 5V power, while the one that worries those upgrading to Haswell is 12V. When PSUs allow a motherboard to provide USB power while 'off,' they turn off some portions while leaving others active - it's why the fan can stop spinning, even though the power supply is clearly still converting mains electricity to DC for the USB ports.
Log in

You are not logged in, please login with your forum account below. If you don't already have an account please register to start contributing.



Discuss in the forums