Report: Not all PSUs support Haswell’s low-power states

So you heard the news: Intel’s Haswell processors, known officially as 4th Generation Core, are coming out on June 3. Users hoping to upgrade will have to set aside some cash for a new processor, a compatible motherboard… and perhaps a new power supply, as well.

Indeed, according to the guys at VR-Zone, Haswell may not play nice with some existing "bargain basement" PSUs. That’s because the chip’s C6/C7 power states apparently require a minimum load of 0.05 amps on the 12V2 rail. The site says not all PSUs have the appropriate circuitry to let the processor sip that little power without the system becoming "unstable" or shutting down. Current Sandy Bridge and Ivy Bridge processors suck a lot more juice—0.5 amps, to be precise—in their low-power states, and meeting that requirement supposedly requires less complex circuitry inside the PSU.

Okay, no big deal. Just check your PSU’s specs to make sure it complies, right? You can try, but VR-Zone says that may not be so simple. "PSU manufacturers (even the enthusiast grade ones) do not usually report the minimum load on their spec sheets," the site explains. Sure enough, the tech specs and manuals on Corsair’s website don’t mention minimum load—and if Corsair doesn’t do it, I doubt cheap and no-name manufacturers bother.

I’m not sure how much truth there is to all of this, but in any case, VR-Zone says motherboard makers "have been told" (presumably by Intel) to include a BIOS setting that disables Haswell’s C6/C7 power states. I guess folks with old and inadequate power supplies may have to live with higher idle power consumption until they replace them.

Comments closed
    • jihadjoe
    • 10 years ago

    Or an even older boat, like the ones some of us Q6600 holdouts are still sailing on.
    =P

    • NeelyCam
    • 10 years ago

    [quote<]Edit 4 - Changed my mind. Promo closes and Neely ships out once we reach -20. Neely?[/quote<] No. -128 or nobody gets nothing

    • NeelyCam
    • 10 years ago

    Can you make them hike the dividend…? If you pull this off, I’ll give you a cut

    • NeelyCam
    • 10 years ago

    Maybe you’re a rat..?

    • NeelyCam
    • 10 years ago

    Maybe have a little kung fu fight with an asian girl wanting to recharge hers

    • Bensam123
    • 10 years ago

    There are a lot of PSUs with a ‘single’ 12v rail… Corsair being a big one pushing it. I can’t imagine them doing something like that if it was out of spec.

    Yes I meant amps, not voltage.

    • willmore
    • 10 years ago

    IIRC, if it doesn’t have a separate 12V rail for the CPU power connector, it’s violating the ATX spec already. Also, this is a minimum *current*, not voltage.

    • ronch
    • 10 years ago

    And I’d look cool at Starbucks too! Good idea!

    • Spunjji
    • 10 years ago

    I don’t know about the world, but I think the dogs are still on XP.

    [url<]http://en.wikipedia.org/wiki/Usage_share_of_operating_systems[/url<]

    • MadManOriginal
    • 10 years ago

    When Haswell launches and exceeds all expectations by light years, causing a huge resurgence in PC sales and profits, you can easily afford this bribery program with your Intel dividends.

    • ronch
    • 10 years ago

    If world+dog has upgraded to Windows 8, does that mean I’m alien?

    • ronch
    • 10 years ago

    In other news, Intel wants people to buy new PSUs that support firmware upgrades that allow them to support the newer Haswell processors.

    And we thought we had to buy a PSU that supports Haswell right away!

    • ronch
    • 10 years ago

    Bribery allowed.

    • ronch
    • 10 years ago

    No. Take it or leave it and get AMD if you want.

    • ronch
    • 10 years ago

    No problem! He’d ship to North Korea if he has to!

    • ronch
    • 10 years ago

    Nope. I’m rooting for AMD, but I’d gladly take a downvote in exchange for Neely giving you a copy of Haswell. LOL

    • NeelyCam
    • 10 years ago

    [quote<]Limit one Haswell Core [b<][i<]i7[/i<][/b<] unit per gerbil.[/quote<] My god... Gordon Gekko lied. Greed is [b<]not[/b<] good!

    • NeelyCam
    • 10 years ago

    [quote<]As soon as we reach our quota[/quote<] What is this - Kickstarter? Nobody gets anything until we hit -128.

    • HisDivineOrder
    • 10 years ago

    If someone upgrades from SB or IB to Haswell, you have to think more than a few of them are going to be doing so for the reduced idle temps and/or cooling requirements. In which case, it’ll matter to them more than a little.

    • flip-mode
    • 10 years ago

    I’ve certainly got no complaints. It’s completely inaudible. I almost got the fanless one, but decided I liked the idea of an essentially quiet fan just for good measure.

    • NeelyCam
    • 10 years ago

    You must be living under a rock if you think that matters: world+dog has upgraded to Win8

    • NeelyCam
    • 10 years ago

    [quote<]Edit - Oh crap.. you know how hard it is typing this post on a tablet[/quote<] You should dump your tablet and get an ultrabook - problem solved!

    • Bensam123
    • 10 years ago

    He was lamenting on the difference from SB…

    Now if you included IB and SB in those estimates, how many computers do you think will really see a benefit from this?

    I skipped SB and went to IB before I went AMD, but I wouldn’t upgrade from either SB or IB to haswell, especially with a nice OC. Once you get past a certain point components become legacy and any sort of upgrade will see a big improvement.

    • Bensam123
    • 10 years ago

    So what happens if you only have one 12v rail? 12v2 would be the second rail unless I’m misunderstanding this…

    Also sorta weird, I got a Apevia PoS PSU for free, and it lists minimum amps… I’ve never seen it on a name brand PSU though.

    • Bensam123
    • 10 years ago

    You know this makes you look like a flaming fanboi right? …for Intel that is.

    • Imperor
    • 10 years ago

    Don’t sweat it. Seasonic (and Enermax) have been my go to for quality PSUs for years and they have yet to disappoint! I have been scourging all data I have been able to access to make this decision and they are often way ahead of the competition, so you’re most likely safe!
    Haven’t checked this issue yet, but wouldn’t be surprised if these manufacturers do post the minimum. They’re just that good! Corsair is just another Brand, buying cheaper series from quality manufacturers, like Seasonic…

    • Imperor
    • 10 years ago

    Will Neely ship to Europe?
    You’re probably gonna get them before us across the pond, so it would be extra sweet to get one mailed pre-release! 😀

    Hmm, maybe I could just sell it and get a whole Steamroller-build in return… 😛

    • bcronce
    • 10 years ago

    Gain compared to what? Compared to the off-state, it will consume quite a bit more power, but compared to a different sleep state, it should consume less power. Resistance in the cabling doesn’t change based on power states.

    • Krogoth
    • 10 years ago

    Pretty much, all of the potential gain you would get from C6/C7 state would evaporate once you throw a heavy load on the PSU via electrical resistance of the cabling.

    • Farting Bob
    • 10 years ago

    Seasonic are very good PSU’s, you shouldnt have any problems. The issue will almost certainly be contained to older units and shitty no-brand ones.

    • smilingcrow
    • 10 years ago

    Good call. That’s a theoretical maximum so it will be interesting to see what it means in real world usage. My PC is usually playing music or doing something even when it might appear to be idle so it rarely even reaches C5 so C6 and beyond seem as far away as Alpha Centauri.
    The main benefits of the extremely low power states (not necessarily C6/C7 but beyond them to the stars) are with operating systems that are more managed than Windows for desktops/laptops so in other words mobile.

    As for a 6W saving you can buy IB laptops that consume around 4W at idle in total so a 6W saving for a desktop CPU alone sounds remarkable.

    • faramir
    • 10 years ago

    It is just short of 6W, actually (0.5A versus 0.05A @ 12V).

    • BIF
    • 10 years ago

    I’m in the same boat as Flip-Mode. I bought a new PSU for my new build because the old one didn’t support sine wave UPS whatever that was.

    I would rather not buy another one so soon just to upgrade my CPU.

    • smilingcrow
    • 10 years ago

    Can I wait for the revised stepping when they fix the USB bugette please?

    • smilingcrow
    • 10 years ago

    Intel has made changes in the past to the power delivery side of things which have broken backwards compatibility. For instance some times the reason why a new platform seems to unnecessarily break socket compatibility at times is due to VRM issues. Intel has chosen to aggressively develop the whole platform and put that ahead of compatibility. They have the resources to do and the vast majority benefit from that as they don’t upgrade CPUs anyway.
    Do you remember when certain motherboards came with removable VRMs although this may have been more with dual socket boards such as Pentium Pro?

    I’ve read some articles recently which suggest that Intel is getting very serious about taking an Apple like approach with regard to attention to detail for the whole platform. They are sending engineers to work closely with OEMs such as Acer and I’ve seen it speculated that one reason for Intel closing its motherboard division is to reallocate those engineers to work on mobile platforms. They’ve been working on optimising touch performance as well and that benefits all x86 platforms so good news for AMD also.

    From a pure hardware level if anyone can match Apple’s approach I’d put my money on Intel. How that actually works in the marketplace is another story as it’s more about software and marketing; not necessarily in that order.
    We can expect some very good hardware from Intel for tablets and for OEMs that work closely with them to optimize the whole platform some good products. The bigger question for me is how well Windows develops as a touch platform.
    Interesting time to be tech watching as the old big two (Wintel) have to adapt or become much less relevant.

    • anotherengineer
    • 10 years ago

    Like it?

    I just got a 460W platinum fanless.

    [url<]http://www.seasonicusa.com/Platinum_Series_FL2.htm[/url<]

    • BIF
    • 10 years ago

    But what if I want to build a dual slot server? Or a quad? Not fair, man! If Neely can give me four processors, I’ll foot the bill for the motherboard and PSU, no problem!

    • superjawes
    • 10 years ago

    This wouldn’t be a failure in the PSU, though. The failure would appear at the mobo/CPU.

    The test you’re describing would be a floating load at the PSU. The failure, if it were to occur, would happen when the PSU was connected to a Haswell system and sources too much current while in a low-power state.

    • gmskking
    • 10 years ago

    Or, you can avoid Haswell altogether.

    • BillyBuerger
    • 10 years ago

    I’m pretty sure I’ve seen some PSU reviews (probably on SPCR) where they test the PSU unloaded. Just grounding the green wire (PS_ON) to trigger the PSU to turn on with nothing plugged in. I don’t think I’ve ever seen a respectable PSU fail that. And if it can handle no load, I don’t see why it wouldn’t be able to handle a very low load.

    I can definitely see crap PSUs having issues here. My guess is that this is just them covering their butts for the cases where people are using crap PSUs. Just like GPUs have a “minimum” PSU wattage that’s way higher than what they really need. They have to take into account that some people have crap PSUs that say they are “600W” when you’ll be lucky if they can really handle half that.

    • Star Brood
    • 10 years ago

    And Ivy Bridge or Sandy Bridge would be almost just as good, and cheaper as they’d be a bit discounted at that point. 1050 is likely to be a dead socket anyway as Broadwell is purportedly on-die only. I don’t think that Haswell is going to be a market mover on the desktop any better than Ivy was.

    Edit: I should add a disclaimer that I am not against Intel or any company for that matter, I’m just trying to play devil’s advocate because, when taken into perspective, there was no reason to wait for Haswell.

    • ronch
    • 10 years ago

    As soon as we reach our quota, Neely’s gonna start pre-ordering the chips. He says it’s either he gives away a hundred of them or none at all. So… be patient.

    Limit one Haswell Core i7 unit per gerbil.

    • derFunkenstein
    • 10 years ago

    I thumbed you down, when do I get the CPU?

    • bcronce
    • 10 years ago

    It’ll be a big jump for me, going from a Gen1 i7 to Haswell.

    The main features of Haswell are much faster IGP and much lower power consumption, both of which don’t affect most enthusiast desktops, like you said.

    Two on-the-side improvements that could help in certain situations are the upgraded AVX and new TSX instructions.

    TSX instructions could make a huge difference for any workload that requires lots of multi-threaded critical paths, like firewalls.

    • Jakubgt
    • 10 years ago

    I currently have a Q9450 in my computer and I’m really looking forward to the launch of Haswell. Small improvement or not, it’s still one heck of an upgrade for me. I’m sure other people are in the same boat as me.

    • ronch
    • 10 years ago

    Not really. I expect most folks who get Haswell to be folks who own setups that are getting a bit old, so getting a new PSU to go with the upgrade isn’t such a terrible way to go. They could just as well pass down their old system to a younger sibling or something. Of course, not having to buy a new PSU is still a nice option particularly for folks who don’t wanna spend unnecessarily for a new PSU. Wait, ain’t we all?

    Edit – Oh crap.. you know how hard it is typing this post on a tablet, then all I get is a downvote? >:(

    • Farting Bob
    • 10 years ago

    This may surprise you, but the vast majority of x86 computers currently in use do not have the latest Ivy Bridge CPU’s. It would be a very big improvement for most systems.
    Having said that, I’m on SB and im going to skip Haswell and then look at a full system upgrade next time and chuck in some DDR4 as well because Haswell on it’s own isn’t worth the cost to me.

    • Star Brood
    • 10 years ago

    I don’t think Haswell is worth the upgrade for most desktop users anyway. Single digit real world percentage improvements speak much louder than all the talked up specs. Sandy Bridge was such a nice step ahead, and in two generations we’ve achieved half of what Sandy did in one. This is getting depressing.

    • superjawes
    • 10 years ago

    [quote<]Anyone who downthumbs this post gets a free Haswell chip courtesy of Neelycam.[/quote<] Free Haswell? At NEELY's expense? Shut up and take my downvote!

    • ronch
    • 10 years ago

    See, there are other ways to make the upgrade path easy aside from socket compatibility! 🙂 AMD is all about innovation!

    • chuckula
    • 10 years ago

    Exactly! Steamroller will definitely not have issues with drawing too little power from the PSU! I’m glad AMD still cares about their customers, unlike Intel!

    • ronch
    • 10 years ago

    No problem. Just get Steamroller.

    Edit – Anyone who downthumbs this post gets a free Haswell chip courtesy of Neelycam. PSU not included though. LOL

    Edit 2 (or should I say, 3) – Oh crap… It’s taking a while for Neely to see this post. Is he still in South Korea? Hope he doesn’t get a fit when he sees this… XD

    Edit 4 – Changed my mind. Promo closes and Neely ships out once we reach -20. Neely?

    • ludi
    • 10 years ago

    In theory, the 12V2 rail should power only the CPU, so if the CPU is drawing an extremely low current, then the 12V2 rail may go unstable. That, of course, assumes (a) the PSU designer actually followed the ATX spec and (b) the motherboard designer actually followed the ATX spec, where (b) is more likely than (a), and neither is guaranteed.

    • swaaye
    • 10 years ago

    I’m not sure how this is a problem. C6/C7 still have the system powered up so there’s lots of 12v load besides the CPU.

    • siberx
    • 10 years ago

    The spec I suspect is mostly an issue to do with stability of the dc-dc converters used in the PSU at low currents, and different/better converter designs wouldn’t be as prone to issues like this. Better caps probably wouldn’t help, but you could definitely work around it by using a small resistor pack to apply a few watts of load to the problematic rail.

    • sluggo
    • 10 years ago

    Yellow wire —- Fan —- Black wire

    Problem solved =)

    • DeadOfKnight
    • 10 years ago

    I think Windows 7 doesn’t support this anyway.

    • Game_boy
    • 10 years ago

    Even if a desktop PSU does support a 0.05amp state, it’s burning far more than the processor just by existing.

    • Krogoth
    • 10 years ago

    This is a non-issue.

    The new power states are meant for laptops not for desktops. Besides, Haswell can still handle S3/C1E just fine (most desktops operate under this). In the worse case, you just have to force the BIOS/EFI settings to use S3/C1E instead of C6/C7.

    • Dysthymia
    • 10 years ago

    Uh-oh. I already purchased a Seasonic S12II 620 and Seasonic G Series 550… Saving on the power bill over the next few years was one of the reasons I was waiting ’til Haswell.

    • superjawes
    • 10 years ago

    As smilingcrow pointed out, if it’s a big enough issue, motherboard makers will probably disable by default, and it won’t be that big of a deal for desktop users. Laptops should be fine.

    For the PSU makers, I’d be curious to see how many meet the spec. I’m no expert, but I am guessing that the minimum currents are coming from capacitor leakage and can be reduced by using better caps or a couple resistors in series.

    • flip-mode
    • 10 years ago

    Nope; sarcasm.

    • smilingcrow
    • 10 years ago

    Just disable C6/C7 in the BIOS; it’s hardly an issue with desktop systems. All these extra power states are more for ultra mobile for better battery life. Saving a watt or less on a desktop doesn’t warrant an upgrade. If it’s a major issue expect motherboards to ship with them disabled by default.

    • chuckula
    • 10 years ago

    Do PSUs even have firmware that is user-programmable?

    • deinabog
    • 10 years ago

    Interesting. It looks this feature will need to be mentioned as a spec on future power supplies. It’s also looking as though the move to Haswell processors will require a bit more planning on the part of users too.

    • flip-mode
    • 10 years ago

    First thing I’d like to know: can I just get a firmware update for my PSU? I hope the Seasonic X560 supports this, as I purchased this high-end beauty within the last year and hoped to have it for years to come.

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