Intel Core i “Haswell” CPUs May Require New Power Supply Units for PCs

Perhaps someone will helpfully design a "PSU stability dongle" comprising a 26.1 Ohm resistor (standard 1% resistor value sufficient to ensure &#62;450mA from 12V) and a Molex connector. Make it a passthrough.<p>Of course, it'll have to be a &#62;5W resistor, but that's what I like to call an opportunity to excel: just more room to add some rakish heat sink fins. You could even spend some of your power wasting budget on LEDs instead, but obviously we'll have to charge more for that model. The margins, you see.

Only if you want the C6/C7 states, which are the really low power draw ones. If you're the kind of person who builds your own PC, it's unlikely you really care about saving a few watts while in sleep. At worst, you'll get Ivy Bridge-level power consumption.

&#62;<i>As it appears, end-users will either have disable low-power states of Haswell or get a new power-supply units compatible with the new Intel chip.</i><p>Errr, is not like many end users update their desktop PC with new CPUs anyway.<p>And those very few that do, they also buy a new motherboard, so to get a new power supply is nothing significant in comparison.

I'm still perplexed why Intel doesn't redesign their CPU socket to be more efficient at delivering power. They're channelling a lot of juice through some very tiny pins or pads, a fairly straight-up evolution of the old 8088 chip that fit into a DIP socket.<p>Is it somehow not practical to have several bigger pins for power that can handle more current than to have literally hundreds of pins dedicated to power? A surprising percentage of the pins on a modern Intel chip do nothing more than power the chip. The traditional pair of +Vcc and GND pins just can't cut it, apparently, and no wonder with some chips drawing over 100W of power.<p>Not too long ago video cards started taking a direct feed from the PSU rather than relying on the PCI or PCIe bus. It's surprising the same thing hasn't happened to high-power integrated circuits.

Just how much of the system is getting shut off in these new C-states? A lot of the best power supplies have a single 12V rail, and the 3.3V and 5V rails are provided by stepping down the voltage from the 12V rail. It seems like any PSU with that kind of design wouldn't be affected unless the total system power consumption drops below 6W, which would require shutting off at least the expansion cards, disk drives, any power-hungry USB devices, and potentially the case fans. Even 4 DIMMs plus the keyboard and mouse necessary to wake up the system might be sufficient to keep the power draw high enough.

I'm going to make a wild guess that the C6/C7 states are intended to be used in notebooks and other battery powered devices. For desktops the rest of the system will easily loose 5W somewhere else.

FTA, quoting Robert Pearce: <i>"I fully expect the [motherboard] companies to disable C6/C7 in the BIOS (though consumers could enable it if they chose to) as there are simply too many PSU's in the market space which might not work correctly."</i><p>... because the motherboard manufacturers can't figure out how to stuff a 240 ohm resistor across the 12v rail?<p>Edit to be fair: if the power savings from going from the legacy suspend to the Haswell states is less than 600mW, then this isn't worth it and disabling the Haswell states is the right solution. In my experience though, PC motherboards almost never idle at less than 3-5W.

It's surprising that these kinds of hiccups happen as infrequently as they do.

The difference between a 0.5 amp minimum current on the 12 volt supply and the 0.05 amp minimum current on the CPU might be enough to power a CPU fan (such as the Precision 690 from Dell, which is about 0.45 amp at 12V). I'm not familiar with other hardware requirements or constraints, so it might not work.

After how many years of standby will the savings of the low power state justify replacement on a 200$ PSU that is 80+ platinium rated? And anyway power states must be disabled for decent overclock to be achieved.

Couldn't Haswell motherboards automatically test the PSU on bootup?

Hmmm. Maybe if they change the socket interface the new mobos can deal with this issue.