question about underclocking

[ThePiston]

I have a small office so I can't have a lot of heat of noise. I usually use a T CPU for my servers (4 in my office) and they are almost silent boxes (45W max TDP).

I do need power though for some DVD conversions and other stuff.

I'm considering getting the 4770K and then underclocking it most of the time. When I need to I want to be able to flip a switch in BIOS (or in Windows if the mobo software will allow) and crank it up when needed.

Is that possible? Anyone care to share what I'd do to convert the 4770K to a T version in the BIOS?

Also, what mobo company has the best UEFI to make these changes on the fly?

Thanks

 

[dave_the_nerd]

To "convert" to a -T version, you'd just lower the max multiplier and voltage. You can even go further down if you want.

Although you really probably don't need to. If Haswell is anything like IVB, it'll downclock and undervolt itself to -T levels when it's idle anyway, then spool up when load increases. (My 3570k idles at 1.6GHz & 0.8-something volts.)

The only reason you'd need to underclock is if you want your system to be <X TDP under load except for the specific times when you're encoding DVDs, etc.

If you have a big batch encode job, why not just set it up to run overnight and leave it at that?

I don't know if there's more better stuff out there, but AsRock's UEFI interface is adequate.

 

[ThePiston]

I'm worried about the heat and fan noise from the K versions. I guess I could always set it to power saving mode and then take if off that when I need it to perform.

thanks

 

[SammichPG]

I'm worried about the heat and fan noise from the K versions. I guess I could always set it to power saving mode and then take if off that when I need it to perform.

thanks

Since it's for work don't bother, underclocking (and undervolting) involves the same stuff that happens for overclocking .. just reversed

Buy a non k part and with the saved money buy a budget after market cooler with a silent fan.

 

[sm625]

Use throttlestop. Just open the program, set up a profile how you want it. (If you have a wattmeter you can use that to help you tweak for lowest possible power). Once you have your profile set up and saved, close throttlestop and create a shortcut to throttlestop and place that shortcut into your startup folder. Then it will be slow by default. If you want to do something that requires more performance, you can activate another profile. In the options you can even set it to start minimized, and to use whichever profile you want.

Using throttlestop, I can make my computer go from an 18 second super pi to a 148 second super pi. Too it is just a core 2, so it only saves about 30 watts.

 

[Concillian]

Buy a 4770k or even non-k and get a large tower cooler with a PWM fan. Set the BIOS up so it keeps the fan at low speed unless it heats up.

The CPUs will run low power unless they're being highly utilized, so the only time it would use it's extra power is when you're encoding. It might get noisier then, but I would think that a cooler like a Noctua D14 or other top tier air cooler would be able to run stock clock speeds very quiet even at high load. In fact, I'm sure of it based on my experience with a 3570k and Noctua. The Noctua comes with resistors so you can run low speed all the time, and you don't even need to rely on the BIOS, which is what I do, even though overclocked some it can handle the heat fine without going full speed.

Most any BIOS from ASUS or Gigabyte or MSI or ASRock will handle automatic speed control of a fan plugged into the CPU fan slot of the motherboard based on CPU temperature... but like I said, with the right cooler, you don't even need that.

 

[ThePiston]

I know I can get fans that are silent, but that doesn't mean the CPU won't be throwing off a lot of heat. I'll have 4 servers in this small office so the less heat the better.

Anyone know what the wattage is on a 4770K running in power saving mode (in UEFI)?

 

[notty22]

As mentioned
Use a power profile in windows. Haswell has a lower clock/voltage than previous Intel offerings, even better. You don't have to 'underclock'.

You can set max cpu usage to less than 100% if needed. There is a min and max setting.

For example the Default High Performance usage for min/max cpu usage is 100%

 

[zir_blazer]

If you aren't going to overclock, the non-K version suits you better. Its 10-20 U$Ds cheaper and you're not missing some features that you're losing on the K series (VT-d, vPro, TXT and TSX) in exchange for the Unlocked Multiplier.


Power consumption (REAL power consumption, not TDP) should be very similar between a Core i7 4770 and a similar T series running at the same Frequency and Voltage. There should be some variance due to the individual dies characteristics (Maybe the T series dies are specifically binned for low leakage and they use the best ones), but I don't think it could make any major difference.
However, if you are going to purchase a big Processor to underclock/undervolt it, you should also consider purchasing a cheaper, smaller one. Exception are if you're expecting to have to ramp up Frequency to the maximum for some workloads.

Also, I don't know details on Intel platforms, but even on AMD 45nm K10s (Athlon II/Phenom II), Cool'n Quiet PStates were subpar compared to what you could archieve by manual tweaking. You could get either better Frequencies at that Voltage or lower Voltage for that Frequency than the default PStates, or even get below those values. So if you're going to tinker with your new Processor, you may find it that whatever default values it got, you can go significantly lower than that if you want the lowest possible power consumption.

 

[Concillian]

Anyone know what the wattage is on a 4770K running in power saving mode (in UEFI)?

At idle it will be the same as whatever the low power version is.
The TDP relates only to the full power operation. Idle power consumption (and heat dissipation) is essentially the same for all chips in the family.

This is why the low power chips make almost no sense in practice. It's only a benefit in two scenarios:
1) you have software that will cause 100% utilization on a core regardless of how much it needs (generally poorly implemented software, for sure, but I have seen this happen)

2) You have a hard limit on max current capacity. Like you are metered & charged by max current drawn in an offsite facility or you need x servers to safely share one circuit breaker.

The normal chips are better overall implementations for power consumption.
Overall power consumption goes down when you have a higher "top speed."
This is because whenever you have power applied to all portions of the chip, you have leakage on all portions of the chip. But in the idle states, you can remove power completely, and thus remove the wasted power/heat. You are never using ALL of the CPU 100%, so your best bet is to complete a task quickly, then get back to idle ASAP. Search the main site for "race to idle" There are a couple server related articles on this. It all sounds very counter-intuitive, but is actually pretty well known at this point.

Total power consumption (and therefore total heat produced) is actually lower with a normal CPU than with a "low power" CPU.

So since the low power version and the regular version are generally the same price, or very close to it, then you should get the normal CPU unless you have specific constraints on current draw that limit you to the low power version.

 

[zir_blazer]

1) you have software that will cause 100% utilization on a core regardless of how much it needs (generally poorly implemented software, for sure, but I have seen this happen)

This is the norm for old games.

The normal chips are better overall implementations for power consumption.
Overall power consumption goes down when you have a higher "top speed."
This is because whenever you have power applied to all portions of the chip, you have leakage on all portions of the chip. But in the idle states, you can remove power completely, and thus remove the wasted power/heat.

I don't entirely agree with this. That sounds on the line of the people that says that a faster, power hungrier chip could be better that a low power one if its finishes the task faster to enter Idle mode again, but its a bit more complex, because it depends on what part of the Frequency/Voltage curve they are.
Power consumption scales almost linearly until a break point where it rises exponentially because you need massive amounts of Voltage for a weak 100 MHz or so increase. Lets assume that you have the following Power States on the same chip on Full Load:

A - 1 GHz, 20W power consumption
B - 2 GHz, 41W power consumption
C - 3 GHz, 65W power consumption
D - 4 GHz, 100W power consumption

Assuming that you have an application scales linearly with Processor Frequency, specifically, one that perform a task (Encode a video, compressing a file) and goes back to Idle, whatever times it takes to complete, A will ALWAYS be the most power efficient. Its the best one in case you want to have your machine do that type of crunching while you're not on the computer and you know that it will be finished when you're back. B is also an exellent choice for minimal extra power consumption, or old games that always put a Core on Full Load.
C would be for modern games, and D when you need to finish something ASAP or need every extra FPS in a game that you can get. You don't want applications, like those that always put a Core on Full Load, to use the D Power State if they can do the same thing on a lower one.

 

[Concillian]

You can make up any data to fit your conclusion or you can look at real world scenarios.

In reality things are not so simple. I invite you to read some of the anandtech IT CPU articles that discuss this in more depth.

For example here: http://www.anandtech.com/show/2919/10
The x3470 balanced is consuming 43% more power at load, but doing over 50% more work than the L3426.
And at full performance turbo it's consuming 55% more power, but doing about 70% more work.

It's overall most efficient at it's max turbo... this is real world data that does not match with your assumptions. Sorry, the real world simply does not work like your assumptions.

At some clock speed and voltage, yes, you go "beyond the knee," but the normal stock speeds of Intels modern CPUs are not "beyond the knee." If they are, they're so close to the ideal speed that it's irrational to chase the extra 5 or 10 watt-hours you'd save in a day and discard the extra performance that the faster CPU would give.

He has already stated a desire for more performance, and I maintain that he should just buy a 4770 (or 4770k) motherboard and high end quiet cooler, plug it in and forget about everything else. Any benefit from using a low power CPU or fiddling around in the BIOS to have a "power user" state and a "low power" state is either non-existant or so minimal that it's not worth the effort.

 

[zir_blazer]

You can make up any data to fit your conclusion or you can look at real world scenarios.

In reality things are not so simple. I invite you to read some of the anandtech IT CPU articles that discuss this in more depth.

For example here: http://www.anandtech.com/show/2919/10
The x3470 balanced is consuming 43% more power at load, but doing over 50% more work than the L3426.
And at full performance turbo it's consuming 55% more power, but doing about 70% more work.

It's overall most efficient at it's max turbo... this is real world data that does not match with your assumptions. Sorry, the real world simply does not work like your assumptions.

That is why I said:

That sounds on the line of the people that says that a faster, power hungrier chip could be better that a low power one if its finishes the task faster to enter Idle mode again, but its a bit more complex, because it depends on what part of the Frequency/Voltage curve they are.

You do NOT know in what part of the Frequency/Voltage curve those Processors sits at. If you are manually tweaking, chances are that you will stick to the lowest possible Voltage that you can and still be rock solid, while chances are that Intel is using Voltages way higher that it could for the low power variants.
Besides, Turbo doesn't modify the Voltage, and more Frequency assuming you already paid the power consumption increase that more Voltage brings is cheap.

Want real world data? Check here. The Processor-only power consumption values for his Sandy Bridge (Picking the lowest one for a given Frequency, and removing 130W that is the power consumption of the rest of his system) are:

2.0 GHz @ 22W
3.0 GHz @ 47W 50% more Frequency for 114% more power
4.0 GHz @ 96W 33% more Frequency for 104% more power

At the best case scenario, the 4 GHz Processor would do a task twice as fast, or at half the total time, of the 2 GHz one - but consumed twice the power that if the 2 GHz one that had to work twice the time.

The problem here is that on real world scenarios, you have to take into account the total system power consumption. All the other system parts will be consuming the same power regardless of if the Processor is at 2 GHz or 4 GHz. Considering that on many machines the other components could consume as much as a low power Processor by itself, these numbers do add up. If you add in the 130W system power to the previous values, you get 2 GHz @ 152W and 4 GHz @ 226W. Suddently, the latter makes sense - but that is NOT because the Processor is more efficient at higher Frequencies, it is much, much worse, but because you are already spending a whole bunch of power on the other parts just to have the machine turned on, on the first place.

 

[kmurkey]

I have been trying to find a way to make a silent computer, and of the thing i thought of is underclocking or buying a T chip (lower tdp > less heat > more silent cooling).

But after months of looking for T chip (nowhere to be found in this country), and insufficient funds to buy intel K chip, i realised the best solution are really quiet fans. I bought Thermalright Venomous X Silent Edition (you can't hear it even with your head next to an open case, amazing), and installed 4 noctua ULN twelves with ULN adapters (i needed some extra cooling since i have 125 tdp X6, but with Intel i don't think you need so many). I can't hear it during the day and it's cold as ice.

Maybe it's a more expensive solution, but you will not bang your head and waste time with undervolting.