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PSU Requirements for lightweight computer? - Page 2  

post #11 of 40
Quote:
Originally Posted by hellonwheelz View Post
Why wouldn't you worry about the brick... With a CPU TDP of 65w, you should be able to surpass the limits easily. I know my laptop is a 32nm intel dual core and it has a 95w brick, (part of that is to charge the battery I'm sure)
Because it doesn't work that way.
A few points here:
TDP is no indication of power draw, but only heat output measured in watts.
The brick is only giving a charge to the system essentially so it's fine to use it with the PicoPSU 120; these are specially designed units that are meant to work together. If they didn't, we would be recommending them or using them.

Mini box would also have a lot of angry customers if they didn't work right.
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post #12 of 40
On a processor the heat output IS the power draw. If your processor is giving off 65w of heat you best believe it's drawing 65w electricity.

Intel also allows peak draws ABOVE the 65w TDP. A quick power budget would be 65w for the CPU 8w for the HD, dvd, 2w all the usb ports. and the motherboard needs some juice too.

intel>>>>
"It is important to note that thermal design power is the maximum thermal power the processor will dissipate, but not the same as the maximum power the processor can consume. It is possible for the processor to consume more than the TDP power for a short period of time that isn’t “thermally significant”. For example, a processor might consume slightly more power than the rated TDP value for say one microsecond…but then consume less power than the rated TDP value for a long period of time."
post #13 of 40
Heat Output IS NOT POWER DRAW.

You can output 65w of heat, but draw over 200. For that matter, while TDP may be amount XX it does not mean you'll actually hit TDP with normal loading.
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post #14 of 40
Quote:
Originally Posted by Tator Tot View Post
Heat Output IS NOT POWER DRAW.

You can output 65w of heat, but draw over 200. For that matter, while TDP may be amount XX it does not mean you'll actually hit TDP with normal loading.
As I understand it, the rest of that 200w draw will end up as heat. Still that would not help your case, If a the power draw from a cpu is greater the TDP where does that leave a 60w brick powering a 65w cpu and the other components.

TDP according to intel is the amount heat needed to to be dissipated running real applications.

The system in question can use 85w sustained in real applications before you even calculate the motherboard power requirements.
post #15 of 40
Intel likes to err on the side of caution. A lot. The TDP is the theoretical maximum amount of heat that can be emitted by the chip when under maximum stress, assuming that it is running at the highest specified VID. Additionally, TDP is usually calculated for the flagship chip in a particular series only, and then the chips below it tagged with that number as well.

For instance, a Q9550 has a stated max TDP of 95W. However, that 95W figure was calculated for the C1 revision of the 3.0GHz Q9650 running at the Wolfdale core's maximum VID of 1.3625V.

For an E0 Q9550 running at stock 2.83GHz with a VID of 1.2125V (mine before overclocking), the actual heat put off by the chip under maximum stress might be more like 45-50W; and power consumption around 60-70W (the power not dissipated as heat is either returned to ground or used for signaling).

You have to know what the numbers actually mean; not just what's stated in the official white papers.
post #16 of 40
Some points are yes true. However some people will have a chip that has the highest vid. And intel state you can use MORE power than the TDP with programs that are not "real applications" and certainly more watts Peak power.

I don't think you have the physics background to claim that electricity used for signaling is not put out as heat. And how can you draw power and return it to ground. Can we have an electrical engineer put this to rest?
post #17 of 40
Quote:
Originally Posted by hellonwheelz View Post
Some points are yes true. However some people will have a chip that has the highest vid. And intel state you can use MORE power than the TDP with programs that are not "real applications" and certainly more watts Peak power.

I don't think you have the physics background to claim that electricity used for signaling is not put out as heat. And how can you draw power and return it to ground. Can we have an electrical engineer put this to rest?
lol your talking to 2 of the best PSU guys on here. they know there stuff.
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post #18 of 40
Quote:
Originally Posted by Blue Destroyer View Post
lol your talking to 2 of the best PSU guys on here. they know there stuff.
Well yes one of is is wrong, I'm just not sure that its me.

For instance...

Quote:
Originally Posted by Phaedrus2129 View Post
The TDP is the theoretical maximum amount of heat that can be emitted by the chip when under maximum stress, assuming that it is running at the highest specified VID.
That "maximum theoretical" is flat out wrong, don't listen to me it's what intel says

http://www.intel.com/performance/res...fs/tdpvacp.pdf

Quoting intel>
It is possible for the processor to consume more than the TDP power for a short period of time that isn’t “thermally significantâ€.

- It is possible to write “virus-like†code that toggles transistors in the processor on and off, but doesn’t do any real work. Such “virus-like†code could cause the processor to exceed the rated TDP value for a much longer, “thermally significant†period of time.
post #19 of 40
Quote:
Originally Posted by hellonwheelz View Post
Quoting intel>
It is possible for the processor to consume more than the TDP power for a short period of time that isn’t “thermally significant”.

- It is possible to write “virus-like” code that toggles transistors in the processor on and off, but doesn’t do any real work. Such “virus-like” code could cause the processor to exceed the rated TDP value for a much longer, “thermally significant” period of time.
So you can cause peak draws that exceed TDP for less than a second, or you can write "virus-like" code designed to overheat the CPU.

I don't think either of those scenarios are important enough to consider here.


The TDP is a power envelope. It is not an absolute figure of what the CPU draws or emits. And Intel overestimates (in their non-laptop chips at least) to give themselves and their OEM partners a margin of error. It's in Intel's best interests because it will lead their partners and customers to overengineer/overestimate cooling and power requirements, which will lead to lower RMA rates, both caused by thermal damage and by PEBKAC.



I will say I don't know what TatorTot is talking about with the 60W power brick, Jonny only tested 102-120W bricks with his PicoPSUs.
Edited by Phaedrus2129 - 3/23/11 at 8:55pm
post #20 of 40
Youre the one using the words "theoretical maximum", peak means maximum, how can you have a maximum above the theoretical maximum? Since you can't, would you please just admit you on that point you misspoke.

Who would run virus like code? Cough, linpack, cough benchmarks.

Quote:
Originally Posted by Phaedrus2129 View Post
So you can cause peak draws that exceed TDP for less than a second, or you can write "virus-like" code designed to overheat the CPU.

I don't think either of those scenarios are important enough to consider here.


The TDP is a power envelope. It is not an absolute figure of what the CPU draws or emits. And Intel overestimates (in their non-laptop chips at least) to give themselves and their OEM partners a margin of error. It's in Intel's best interests because it will lead their partners and customers to overengineer/overestimate cooling and power requirements, which will lead to lower RMA rates, both caused by thermal damage and by PEBKAC.



I will say I don't know what TatorTot is talking about with the 60W power brick, Jonny only tested 102-120W bricks with his PicoPSUs.
The TDP is exactly what intel says it is. They sell chips (not all, of course) that will draw and dissipate TDP continuously and even exceed it.
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