Aggressive undervolting (X41 Tablet - Pentium M 758 LV)

[Investinwaffles]

Ok, So I am aggressively undervolting my X41 tablet to see if it there are any real world benefits.

So far, my voltages for the Pentium M 758 LV (1.5ghz, 2MB L2, 400mhz fsb) are:

6x @ .796V (.988V originally)
8x @ .876V (1.020V orig.)
10x @ .892V (1.052V orig.)
12x @ .908V (1.068V orig.)
15x @ .924V (1.116V orig.)

Program: Notebook Hardware Control (voltage & temps)


I have noticed a drop in idle temps (Idles at .796V @ 40-42*C - 1hr runtime, idle), and a drop in load temps (.924V @ 64*C - Prime 95 Torture Test 2 Hrs)

Do you guys think undervolting is a good thing, or should i just leave them stock? As far as i can tell, it has been reliable (i dont really stress it, but reliability is always good). Should i go for even lower voltages?

Also, what is the actual difference between the 1.5ghz and the 1.6ghz? On my dell m170, you can pinmod the processor to trick it into clocking higher (1.7-->2.1ghz). Can anything like that be done on the x41t? The HDD is the bottleneck currently, but i plan to fix that with an SSD of some sort and will take any boost in speed i can get.

Full Specs:
X41 Tablet (PM 758lv, 1.5gb ram, 60gb 1.8" 4200rpm hdd, XP tablet pc edition).

EDIT:
ALSO Can people please post up temperatures for their X41 tablets? Stock and undervolted would be appreciated (if there is anyone else out there undervolting).

[Investinwaffles]

Also:
No battery figures because my 4 or 5 cells have failed in my 8 Cell battery, but i can only assume a noticeable increase in battery life.

Does anyone have a REPUTABLE vendor i can get an 8 cell from, without spending an arm and a leg? I was looking at the 4500mah batteries on ebay but I am very wary...

[tim S]

I have an X40 and an X41 both have 1.6Mhz CPUs and both get unpleasantly hot on my lap after about 10-15 minutes!
The X40 runs Windows XP SP3, while the X41 runs Kubuntu Hardy and there is no difference. Not exactly a scientific test but they, or at least the 1.6Mhz models, run really hot on the underside.
As to batteries, I've had no problem with eBay vendors but I do stick with genuine IBM batteries. Unfortunately since these laptops are no longer in production the batteries are also quite old, even if they are new.
I had a very easy transaction with 'jadescomputer' who has 20,053 transactions with a 99.7% positive feedback. A genuine IBM X40 (regular) battery new for about $32.00, and it arrived in 3 days!
Tim S

[Investinwaffles]

Thanks! I will definitely look for him on ebay.

And this solved my heat problem. After a cold boot (sitting for a while), the laptop never goes past 35*C, and the fan does not come on unless i start using the computer heavily. Moderate useage rarely sees temps higher than 45*C, and my load temps are actually down to 61*C!!

[visionviper]

Undervolting is great - it reduces heat and prolongs battery life (fan doesn't have to come on as often/fast).

[Investinwaffles]

New numbers:

6x @ .700v
8x @ .764V
10x @ .780V
12x @ .844V
15x @ .924V

It is loading at 1.5ghz around 62-63 now, and idling at less than 34*C!!

Until now ive never had this machine idle below 43ish. I cant wait to put some arctic silver 5 on the HSF


Does anyone have a take-apart guide for the x41-tablet? Would be much appreciated, i cant find anything for the table tho (regarding disassembley).

[rkawakami]

The Hardware Maintenance Manual for the X41T is here:

http://www-307.ibm.com/pc/support/site. ... MIGR-60073

[visionviper]

waffles: what are you using to test stability?

[Investinwaffles]

Prime 95 mostly, and 3Dmark03 for a blend (all the components).
It ran for 29 hours with zero errors on prime 95 torture test (switching the multiplier every now and then to make sure it is stable across the board).

I would highly recommend this mod. Im planning on removing the heatsink, cleaning it up and putting some AS5 on there.
I'll report back with my results

[ricerocket]

So undervolting uses a lower voltage for different multipliers, but theoretically the performance should stay the same, correct?

[Investinwaffles]

Higher clock speeds require higher voltages.
For instance, using a 6 x multiplier yields 600mhz @ .700v
while a 15 x multiplier, yielding 1500mhz needs .924v.

[aaa]

So undervolting uses a lower voltage for different multipliers, but theoretically the performance should stay the same, correct?

It's not just theoretical, that's the way it actually works.

[visionviper]

So undervolting uses a lower voltage for different multipliers, but theoretically the performance should stay the same, correct?

It's not just theoretical, that's the way it actually works.

Exactly. Reducing the voltage really just only reduces heat and reduced heat leads to better battery life (fan doesn't have to work as hard). Performance stays the same.

[ricerocket]

Are you guys using NHC or RMclock?

NHC complains about not being able to change modes in Vista SP1.

RMclock will change your Sleep into Hibernate, which is sorta annoying.

[visionviper]

Are you guys using NHC or RMclock?

NHC complains about not being able to change modes in Vista SP1.

I have only ever used NHC on XP. It might be a permissions issue - where you need to run NHC as administrator.

[ricerocket]

No dice.

[tomh009]

NHC should work on Vista ... but, alas, it is no longer actively developed or supported -- the last pre-release was just about two years ago.

So you did "Run as administrator" and you're still getting the same errors?

[Investinwaffles]

I use NHC because im more familiar with it, and I like its "dynamic switching" mode where i can set how much CPU load it takes for it to upclock.

And after more tweaking my final temps are as follows:

Load (1hour Prime 95 torture test) : 53*C
Idle (for 1 hour after the computer was loaded): 39*C

And from cold boot -> idle it stayed at an amazing 34*C for almost 30 minutes! Then it slowly creeped up to 37*C and stayed there. this was after a COLD BOOT though, not quite real-world but still impressive.

2 hours of light use (office, outlook, firefox, etc) kept the cpu around 41*C, and it would come back down to 39*C after i let it sit for a minute or so.

The fan hardly comes on now, and everything runs cooler including the HDD.

I really really need to apply some arctic silver, as the stock thermal compound/pad is really killing the performance. All in all, i would highly reccomend this to anyone with PM processor, more so the LV versions because they can do amazing things (such as .700v ).

I have done a collective 50 hours of prime 95 loading using different multipliers and it seems rock solid.

[Investinwaffles]

Also, can someone explain the thermal design of the X41-t?

There is no large fan intake, so it must be bring air in from smaller holes spaced along the body of the computer. Does it bring fresh air through the computer?
Specifically, does it bring in any cool air through the RAM area?

Im trying to set up my fan triggers for two profiles, one mobile and one at my desk. I dont mind the noise when its sitting there, and if it is cooling down the whole computer via air intakes it would be worth it to me.

[TheRedFox]

does anyone have any really crazy awesome stable values for a 1.8ghz donthan cpu?
currently fairly aggressively undervolted at (in multiplier:vids) 18:26 16:20 14:15 12:11 10:6 8:2 6:1
i got the values off of thinkwiki, and it appears stable, though I couldn't say for sure.

[zhenya]

Are you guys using NHC or RMclock?

NHC complains about not being able to change modes in Vista SP1.

RMclock will change your Sleep into Hibernate, which is sorta annoying.

NHC does not work under Vista SP1. There is a Beta 2.0.7.3 version available (google search should find it for you) that works, but it ONLY allows CPU voltage control at this time (ie. none of the other normal NHC functions work).

I use NHC on my z61t for the same reasons as everyone else here, but NHC has never allowed me to undervolt the lower multipliers (ie. the base value is 0.95v, and I don't have a choice to go any lower). I see that some of you are doing this successfully. Is there something I'm missing, or are different cpu's just handled differently?

[aaa]

does anyone have any really crazy awesome stable values for a 1.8ghz donthan cpu?
currently fairly aggressively undervolted at (in multiplier:vids) 18:26 16:20 14:15 12:11 10:6 8:2 6:1
i got the values off of thinkwiki, and it appears stable, though I couldn't say for sure.

Use prime95 to check at each speed, run the torture test for 10mins (or 12hours each if want to be thorough ). That is pretty low already, so it isn't worth it to try going the one available notch lower. Just check what you have.

I use NHC on my z61t for the same reasons as everyone else here, but NHC has never allowed me to undervolt the lower multipliers (ie. the base value is 0.95v, and I don't have a choice to go any lower). I see that some of you are doing this successfully. Is there something I'm missing, or are different cpu's just handled differently?

The pentium M lets you undervolt all the way, all the newer Intel cpus block you from going below default for the lowest speed (you can only change it for the higher speeds).

[zhenya]

The pentium M lets you undervolt all the way, all the newer Intel cpus block you from going below default for the lowest speed (you can only change it for the higher speeds).

Ahh, that's too bad as the computer is perfectly stable at the lowest 0.95v for all but the highest multiplier. There is definitely room to go lower. Thanks for the info!

[TheRedFox]

I stress tested 600 1600 and 1800mhz, so far. the 1600mhz was after applying cooling paste. they were all stable. 1600mhz stayed at a fairly low temp. a little under 60 degrees. 600mhz of course didn't get very hot, but 1800mhz peaked at a worrisome 82 degrees... maybe it'll be better since the cooling paste. although 600mhz doesn't seem to be getting better. it's currently 47 degrees unplugged, and that's about the same as usual (usually 48 plugged in, and a little cooler unplugged)

[Investinwaffles]

Are you undervolting the CPU?
The 1.8's are not low voltage so that is where the extra heat is coming from, plus the laptop's cooling system is small and simple (one heat pipe for the CPU).

Try a program such as TP Fan Control to dial in your fan turn-on temps and speed. My computer idles at 38*C, and the fan turns on at around 40*C.

Generally when im doing moderate surfing (youtube, flash games, etc) it jumps up to around 44*C. Normal internet browsing (ebay, forums, etc) stays around 41*C.

Prime95 load doesnt go above 55 after 3 hours.
I also opened up the vents only by the ram (on the underside of the notebook) to bring more cool air over the ram (as opposed to the modem and wifi card).
No idea if it made a difference but the laptop barely gets warm now.

[aaa]

Yes, I would think that the fan is what's controlling your idle temp. IIRC my X31 would just sit quietly and get hot, then finally turn on the fan after a while. I guess they wanted to make it quiet...

http://www.thinkwiki.org/wiki/How_to_control_fan_speed

[visionviper]

If your having problems with the release on the website - may I suggest a beta version? It was just released in March 2009. It is only for 32-bit Vista (and so would probably also work on 32-bit Windows 7).

[TheRedFox]

The fan turns on at about 55 or so degrees, with the X31 motherboard it was a lot longer untill it turned on, so it got really hot (even with tp-fancontrol, for some reason. it was supposed to turn on at like 55 or something, but it never did.) The X31 mobo idled at a lower temp though, especially when unplugged. this one usually sticks at 48 degress (with cpu governor ondemand), but occassionally will get up to like 55 or so. the fan tends to turn off at about 47 degrees (I haven't used tp-fancontrol yet). occassionally it will stick as low as 44 sometimes when unplugged, but after a while start going up. The RAM seems to be the main issue for heat though (I wish I could undervolt that). perhaps I will try tp-fancontrol and have it turn on the fan at 48 or 49 degrees and turn it off at 44 degrees....

[Investinwaffles]

Well, does the noise of the fan bother you? Iam rarely anywhere quiet enough to even hear the fan on low speed so I have it kick on at 40*C ish.

It keeps the ram, wifi card, processor, and case cooler because the air is drawn in through various vents in the computer. TP Fan control has the option for 2 profiles so i have one set as a low noise profile (fan kicks on at 55*C and stays low until 70*C).

ALSO:
Make sure you check the thermal sensors and disable any that are higher than the CPU. In TP Fan Control, it uses the thermal sensor with the highest temp to trigger the fan (NOT always the CPU). In my machine, the "crd" sensor is always a few *C higher than the CPU temp and would trigger the fan to turn on. This is probably the problem your having.


And I found a solution for the RAM problem. I bought one of these notebook ram heatspreaders and some arctic silver 5 the other day. I will install it (and apply the AS5) and let you guys know how it goes.

[spabwe]

I am a new guy here, I had OC my X32(735 to 780), this is my setting:
6 0.780V
8 0.876V
10 0.972V
12 1.100V
14 1.480V
17 1.340V
Of cource, I didn't use 17X step