Google's Secret Server

ultrachrome · Post by **ultrachrome** » Fri Apr 03, 2009 5:57 am

Google uncloaks once-secret server

While their overall approach doesn't share much in common with SPCR methodology, perhaps their power supply setup could potentially help lower power consumption in all PCs.

For those suffering from short attention span, they use a 12V only PSU. 5V is generated outside of the PSU, if needed, somehow.

Thoughts?

lm · Post by lm » Fri Apr 03, 2009 6:29 am

I don't directly see what else do they save from moving the 12V->5V conversion from the PSU to the mobo than having shorter wires for 5V power.

But if the 5V needs to be further converted to some other voltage, surely it is more efficient to do it directly from 12V without the intermediary step?

Any electrical engineers or similar care to explain?

InfyMcGirk · Post by **InfyMcGirk** » Fri Apr 03, 2009 6:37 am

My initial thought was why haven't mobo manufacturers been offering these boards with support for 12v lead-acid backup and 12v->5v conversion built-in... then I read the bit about the Google patent.

I bet APC et al are a bit worried by this technology becoming public as the efficiency figures are pretty amazing compared to traditional UPSs.

nutball · Post by **nutball** » Fri Apr 03, 2009 7:00 am

April 1st, eh? Hehe, yeah very amusing.

ultrachrome · Post by **ultrachrome** » Fri Apr 03, 2009 7:00 am

lm wrote:I don't directly see what else do they save from moving the 12V->5V conversion from the PSU to the mobo than having shorter wires for 5V power.

But if the 5V needs to be further converted to some other voltage, surely it is more efficient to do it directly from 12V without the intermediary step?

Any electrical engineers or similar care to explain?

I'm guessing it's a simpler PSU. Note the CPU has a 12V input from the battery. Perhaps it's a custom design made less expensive by the single output voltage requirement.

I'm not a EE but perusing the SPCR PSU fundamentals article (a little dated), RAM uses 3.3V, and drives are using 5V.

I would expect/want RAM voltage to be generated by the motherboard, if it isn't already today.

It would be interesting if you could get away with powering dual hard drives serially, giving them 6ish volts each.

Metaluna · Post by **Metaluna** » Fri Apr 03, 2009 7:01 am

lm wrote:I don't directly see what else do they save from moving the 12V->5V conversion from the PSU to the mobo than having shorter wires for 5V power.

But if the 5V needs to be further converted to some other voltage, surely it is more efficient to do it directly from 12V without the intermediary step?

Any electrical engineers or similar care to explain?

I'm an electrical engineer (or similar

). Unfortunately I don't know enough about power supply design to comment authoritatively (I'm more of an FPGA/ASIC guy), but one thing the article mentioned was that, by having only one rail in the power supply, you can run it at a higher load, thus increasing the PSU efficiency. This is one advantage you get by having complete control over the entire system design. You can move subsystems around to where they make the most sense, and tune the system to match your expected power consumption. Contrast that to the commodity market, where you have vendors hawking 1kW power supplies with 8 zillion 12v rails that are powering motherboards that idle at 200W at most.

xan_user · Post by **xan_user** » Fri Apr 03, 2009 7:59 am

Google's first experiments had some rough patches, though, Clidaras said--for example when they found the first crane they used wasn't big enough to actually lift one.

I wonder how much a shipping container with climate control, backup generator and 1160 servers with batteries weighs?

Moon GT · Post by **Moon GT** » Fri Apr 03, 2009 8:00 am

ultrachrome wrote:It would be interesting if you could get away with powering dual hard drives serially, giving them 6ish volts each.

Very dangerous, I suspect. If one drive ever happened to require less current than the other at any time, the voltages could go all over the place.

With fans, however, it is a very real possibility. I was thinking about this the other day.

morpheus · Post by **morpheus** » Fri Apr 03, 2009 8:20 am

I think the use of only 12V makes the integration of the 12V battery easier too.

Moon GT · Post by **Moon GT** » Fri Apr 03, 2009 9:02 am

Actually one could probably mod a Pico PSU or something similar to do exactly the same, power it off your 12V rail and bypass the regulators on the 12V output. Find out which bits of your PSU do the 5V line and remove them.

lm · Post by lm » Fri Apr 03, 2009 12:46 pm

Moon GT wrote:Actually one could probably mod a Pico PSU or something similar to do exactly the same, power it off your 12V rail and bypass the regulators on the 12V output. Find out which bits of your PSU do the 5V line and remove them.

If I understood correctly that you would replace the 5V circuitry of a regular PSU with a pico psu:

If you start with a quality PSU, I don't think you win one bit in efficiency. If you start with a crappy PSU, you could have just spent the money of crappy regular PSU plus pico to a single good PSU and not lose your warranty, and inherently have a less complex and more robust system.

Maybe google can get so high efficiency just because their whole system is designed as a whole, instead of just throwing together random parts. They can measure their power draw distribution exactly, and design a PSU that is optimal to just that power draw distribution. Regular home users don't have this data and they have to go by guesswork and are vulnerable to marketing and local availability constraints.

lm · Post by lm » Fri Apr 03, 2009 12:58 pm

morpheus wrote:I think the use of only 12V makes the integration of the 12V battery easier too.

I am not sure, but I think PSUs in general these days actually do have a AC -> something -> 12V part, and then separate 12V -> 5V and 3.3V part. It should not be much trouble to google to put the battery in between even if the latter part were still inside the PSU.

During the years, number of different output voltages coming from a single PSU has gone down. There used to be more than just the 12V, 5V and 3.3V that are in use now.

But since the devices usually need something different from the PSU outputs and the other devices, they would be best off just converting from 12V always, instead of having 12V -> 5V -> something chain. This would result in a simpler system altogether, and less wire loss because of higher voltage transport to just next to the device that actually uses the power.

morpheus · Post by **morpheus** » Sun Apr 05, 2009 12:40 pm

lm wrote:
morpheus wrote:I think the use of only 12V makes the integration of the 12V battery easier too.
I am not sure, but I think PSUs in general these days actually do have a AC -> something -> 12V part, and then separate 12V -> 5V and 3.3V part. It should not be much trouble to google to put the battery in between even if the latter part were still inside the PSU.

You are probably right. Actually, if I remember correctly, the use of Dc to DC converter for generation of 5V and 3.3V from 12V is advertised as a feature of latest PSUs (Enermax Revolution I think)

Moon GT · Post by **Moon GT** » Thu Apr 09, 2009 11:44 am

[quote="lm"]If I understood correctly that you would replace the 5V circuitry of a regular PSU with a pico psu:[/quote]

I'm not suggesting anybody actually go and do this, I wouldn't think you'd gain very much, just saying that it's effectively what Google has done, having a Pico PSU build into the motherboard. It would certainly save on a lot of wires and transmission losses, considering that the only other things that use 5V or 3.3V are your drives, and they don't use that much. In fact even most SATA drives aren't using 3.3V yet, despite it being in the standards, because so many people are still using molex to SATA power leads, which if course don't have a 3.3V line on them.

A motherboard could quite probably easily run from an 8-pin 12V lead. That would just be so much neater.

bexx · Post by **bexx** » Mon Apr 13, 2009 8:30 pm

This isn't that uncommon. I know Tyan makes some 4way systems that run off coldwatt PSUs I think.... they're basically just 12V PSU and 5VSB... mobo does all further conversions.

Really 12V and 5V is all modern motherboard designs really need, well and 5VSB. Getting rid of 3.3 would be trivial. So little 3.3V power is used it would not be difficult to convert from 12. Basically a standard that used only 12V,5V,5VSB would be very easy to migrate to, the only new things would be the PSU and motherboard. Getting rid of 5V would be much more difficult due to HDD/CDROM/whatever else has a molex connector.