Hi! Please review my calculation of AMD turion power consump

dan · Post by **dan** » Wed Jul 30, 2008 5:00 pm

Hi! Please review my calculation of AMD turion power consumption, thanks in advance.

I bought a compaq presario f730US notebook pc from officemax on sale. It comes with a AMD Turion 64 mobile tk-55, a 65nm dual core cpu with 2*256k L2 cache. Evidentally its TDP is rated 35W.

http://users.erols.com/chare/elec.htm

So when it is on windows high performance setting, it is 9x=1.83ghz, 1.1 volts.

when it is on power save, it is 4x=803mhz, 0.9 volts.

So going from high performance setting to power save, I get,

mhz reduction
4x/9x = 0.44
volt reduction
(0.9v/1.1v)^2 = 0.67

therefore 0.67 * 0.44 = 0.29 or more than a 3 fold reduction in total power consumption (i.e 35 watts/3 = about 12 watts).

I can use RM clock to further reduce the voltage to around 0.7 volts, at 4x multiplier, hence

(.7/.9)^2 = 0.60 or another 40% reduction in power, except that I occassionally get a BSOD at 0.7 volts so I keep it at 0.9 volts.

tehcrazybob · Post by **tehcrazybob** » Thu Jul 31, 2008 3:03 pm

I see two flaws, but they aren't with your math. First, the thermal design power for that range of chips is 31w, not 35w. Second, the TDP is usually the maximum power for the fastest chip in the range, and your chip will use slightly less due to its lower clock speed.

For your range of chips, the TDP is probably based on the 2GHz TL-60. Because your clock speed is 1800/2000 as much, your power will be smaller by the same ratio, 90%. The two chips have different amounts of cache as well, but I expect the difference would be small.

Based on the ratio of your clock speeds, your maximum power is 90% x 31w = 28w.

Next, run your calculations again with that number as a starting point. 0.29 x 28w = 8w. This is your idle power.

dan · Post by **dan** » Thu Jul 31, 2008 4:33 pm

tehcrazybob wrote:I see two flaws, but they aren't with your math. First, the thermal design power for that range of chips is 31w, not 35w. Second, the TDP is usually the maximum power for the fastest chip in the range, and your chip will use slightly less due to its lower clock speed.

For your range of chips, the TDP is probably based on the 2GHz TL-60. Because your clock speed is 1800/2000 as much, your power will be smaller by the same ratio, 90%. The two chips have different amounts of cache as well, but I expect the difference would be small.

Based on the ratio of your clock speeds, your maximum power is 90% x 31w = 28w.

Next, run your calculations again with that number as a starting point. 0.29 x 28w = 8w. This is your idle power.

Hi, I got the 35 watts from that website, but if it is closer to 31 watts, or even 28 watts, so much the better!

Hey I want to say "thanks". So my idle power is only 8w when on power save? cool. Doesn't seem to improve batter life all that much -- i take it the display and non-CPU components must take the lionshare of energy.

When I am on laptop I get 3 hours, so I use RM Clock to undervolt it from the default 4x=803 Mhz, 0.9 volts to 4x = 803 Mhz, 0.7 volts.

I infer going from 0.9 volts at 803Mhz to 0.7 volts saves 8w * (0.7/0.9)^2 = 4.8 or 5 watts. At factory default it uses about 28 watts.

I wish I had XP on this machine but neither nvidia nor compaq offers the drivers I need to do this.

MASTER-ARIES · Post by **MASTER-ARIES** » Thu Jul 31, 2008 11:23 pm

Dear Dan

There are drivers for your laptop f730US, try the following links:

http://answers.yahoo.com/question/index ... 542AAEfRtX

http://forums11.itrc.hp.com/service/for ... Id=1172754

the only problem is bios on certain hp compaq models there is an option in bios to activate sata this allows xp to pick up sata drives, if not you have to build sata driver in to xp boot cd using nlite its free. I suggest building with XP SP2 ISO. Based on your chipset these drivers can be downloaded as xp boots. Do not make it an Unattended installation xp picks up the sata drivers the first time but fails to copy them when in setup stage.

Sincerely

MASTER-ARIES

(MA)

tehcrazybob · Post by **tehcrazybob** » Fri Aug 01, 2008 6:53 am

dan wrote:...i take it the display and non-CPU components must take the lionshare of energy...

The screen especially. If you want to improve your battery life, try dimming the backlight as much as you comfortably can. It could make a pretty substantial difference, especially with a larger screen; I know my screen uses upwards of 7 watts, and it's got a pretty weak backlight to begin with.

Additionally, I think the calculations we've been looking at assume the processor is at full load for the voltage and frequency it's been set at. When it's truly at idle, it can be using even less power, with no way to calculate how much.

dan · Post by **dan** » Fri Aug 01, 2008 9:05 am

MASTER-ARIES wrote:Dear Dan

There are drivers for your laptop f730US, try the following links:

http://answers.yahoo.com/question/index ... 542AAEfRtX

http://forums11.itrc.hp.com/service/for ... Id=1172754

the only problem is bios on certain hp compaq models there is an option in bios to activate sata this allows xp to pick up sata drives, if not you have to build sata driver in to xp boot cd using nlite its free. I suggest building with XP SP2 ISO. Based on your chipset these drivers can be downloaded as xp boots. Do not make it an Unattended installation xp picks up the sata drivers the first time but fails to copy them when in setup stage.

Sincerely

MASTER-ARIES

(MA)

Dear Master-Aries,

thanks for the link. The factory bought compaq has a zillion crapware and trialware from Norton security to office 2007 to help HP and all these IP providers including aol and earthlink. then you go online and find a zillion updates, including updates to all the original factory installed drivers (i.e nvidia, touchpad, etc)

One question I have

for the purpose of deep undervolting, is XP sp3 more stable or vista sp1 more stable (fewer BSOD's)? i understand there is some sort of problem with sp3 and amd.

regards

dan · Post by **dan** » Fri Aug 01, 2008 9:08 am

tehcrazybob wrote:
dan wrote:...i take it the display and non-CPU components must take the lionshare of energy...
The screen especially. If you want to improve your battery life, try dimming the backlight as much as you comfortably can. It could make a pretty substantial difference, especially with a larger screen; I know my screen uses upwards of 7 watts, and it's got a pretty weak backlight to begin with.

Additionally, I think the calculations we've been looking at assume the processor is at full load for the voltage and frequency it's been set at. When it's truly at idle, it can be using even less power, with no way to calculate how much.

Hey thanks. I have it so when it's plugged in its 100 % bright, when its unplugged the bar is around 80%.

Still unclocking and undervolting while it makes the fan turn on less frequently (the fan is nearly constantly on at full blast when vista is set at high performance, it comes on only periodically when under battery save) battery life is not signifcantly extended (maybe like a 30 minute difference).

dan · Post by **dan** » Thu Aug 07, 2008 12:45 am

MASTER-ARIES wrote:Dear Dan

There are drivers for your laptop f730US, try the following links:

http://answers.yahoo.com/question/index ... 542AAEfRtX

http://forums11.itrc.hp.com/service/for ... Id=1172754

the only problem is bios on certain hp compaq models there is an option in bios to activate sata this allows xp to pick up sata drives, if not you have to build sata driver in to xp boot cd using nlite its free. I suggest building with XP SP2 ISO. Based on your chipset these drivers can be downloaded as xp boots. Do not make it an Unattended installation xp picks up the sata drivers the first time but fails to copy them when in setup stage.

Sincerely

MASTER-ARIES

(MA)

I'm going to look into this on the theory that xp will run better on a 800mhz pc 1Gb ram than vista does.

true?

juamez · Post by **juamez** » Thu Aug 07, 2008 1:31 am

dan wrote:
MASTER-ARIES wrote:Dear Dan

There are drivers for your laptop f730US, try the following links:

http://answers.yahoo.com/question/index ... 542AAEfRtX

http://forums11.itrc.hp.com/service/for ... Id=1172754

the only problem is bios on certain hp compaq models there is an option in bios to activate sata this allows xp to pick up sata drives, if not you have to build sata driver in to xp boot cd using nlite its free. I suggest building with XP SP2 ISO. Based on your chipset these drivers can be downloaded as xp boots. Do not make it an Unattended installation xp picks up the sata drivers the first time but fails to copy them when in setup stage.

Sincerely

MASTER-ARIES

(MA)
I'm going to look into this on the theory that xp will run better on a 800mhz pc 1Gb ram than vista does.

true?

1GB ram isn't too bad for vista, but it surely lacks processing power at 800MHz. Can't you set it so that it would ramp up the cpu speeds when needed, and when it's idle again it would ramp down again to minimum needs. Like Cool&Quiet for AMD and Speedstepping for Intel. That way the cpu is done faster doing what it's doing and can go to an idle powerstate in which it draws less power.

This theory all depends on what state is more efficient to handle heavy loads. This can be calculated by taking the power and multiply it by the time it has to be in that state before the task is finished. That gives you Watt*seconds = Joules (since Watt = Joules per seconds). The more efficient powerstate lets you finish the task with the least Joules used up. I think that is (part of) your ultimate aim, no?

dan · Post by **dan** » Thu Aug 07, 2008 6:35 am

juamez wrote:
dan wrote:
MASTER-ARIES wrote:Dear Dan

There are drivers for your laptop f730US, try the following links:

http://answers.yahoo.com/question/index ... 542AAEfRtX

http://forums11.itrc.hp.com/service/for ... Id=1172754

the only problem is bios on certain hp compaq models there is an option in bios to activate sata this allows xp to pick up sata drives, if not you have to build sata driver in to xp boot cd using nlite its free. I suggest building with XP SP2 ISO. Based on your chipset these drivers can be downloaded as xp boots. Do not make it an Unattended installation xp picks up the sata drivers the first time but fails to copy them when in setup stage.

Sincerely

MASTER-ARIES

(MA)
I'm going to look into this on the theory that xp will run better on a 800mhz pc 1Gb ram than vista does.

true?
1GB ram isn't too bad for vista, but it surely lacks processing power at 800MHz. Can't you set it so that it would ramp up the cpu speeds when needed, and when it's idle again it would ramp down again to minimum needs. Like Cool&Quiet for AMD and Speedstepping for Intel. That way the cpu is done faster doing what it's doing and can go to an idle powerstate in which it draws less power.

This theory all depends on what state is more efficient to handle heavy loads. This can be calculated by taking the power and multiply it by the time it has to be in that state before the task is finished. That gives you Watt*seconds = Joules (since Watt = Joules per seconds). The more efficient powerstate lets you finish the task with the least Joules used up. I think that is (part of) your ultimate aim, no?

Um sure, vista and xp offer "balance" between powersave and performance. but since i mostly use my laptop for web broswing and word and spreadsheats, i've done fine wit "battery saver"