Undervolting: how low can you go?

ddrueding1 · Post by **ddrueding1** » Mon Sep 10, 2007 7:16 am

fas_k wrote:Anyone underclocked a pentoum d 945 if so please show clock settings.
vcore settings etc. fsb etc. !!!!!!!!!!!!

You are the one with the chip. Why don't you do it? It isn't rocket science...

ddrueding1 · Post by **ddrueding1** » Mon Sep 10, 2007 7:58 am

ddrueding1 wrote:Intel Pentium M Dothan 1Ghz

Minimum (600Mhz): 0.7v (lowest possible)
Stock (1GHz): 0.748v

This is in my ASUS R2Hv-A1. Using "Notebook Hardware Control", great program.

I just checked and this entire system (including screen at max brightness) draws only 11W! No wonder the battery life is so huge!

Mikael · Post by **Mikael** » Fri Sep 14, 2007 11:00 am

Just in: Pentium Dual Core E2160 (1.8GHz)

I have only had time to do some initial testing so far:

3.00GHz @ 1.30V
2.40GHz @ 1.16V

Sadly, the Asus P5B I'm using refuses to feed this CPU less voltage than 1.16V. I'll be getting a Gigabyte GA-G33M-S2H next week, so I'll get back with minimum voltage at 2.4GHz.

I should also be able to report difference in power consumption between this CPU (also known as Conroe-1M) and the E6600 (also known as Conroe-4M). Could be interesting.

For the ones interested, this CPU achieves 1530 points per day running folding@home (SMP, 2653 WU) @ 3.00 GHz. Pretty good folding power for an 80 dollar CPU.

ryboto · Post by **ryboto** » Sat Sep 15, 2007 11:12 am

Well, i need to make an addendum to my previous results. I upgraded to 4x1gb of DDR2, from 2gb, and I wanted to maintain the same power consumption whist running the ram at ddr2-800(silly am2 half multipliers). I haven't tried a lower vcore yet, I'll attempt it eventually.

new setting,
AMD X2 4000+
2.0ghz 1.008v

papakoo · Post by **papakoo** » Sat Sep 15, 2007 12:33 pm

darkbulb wrote:
ryboto wrote:So, here are my results,

Athlon X2 4000+ 65W Brisbane

Minimum: 1.0ghz @ 0.856v
Stock: 2.1ghz @ 1.031v
New Athlon X2 4000+ 65W Brisbane user myself.
Minimum: 1 GHz 0.864V
Stock: 2.1 GHz 1.056V

My board also seems to be adding 0.006-0.014 V.
At 2.1GHz, going any lower than 1.05 in RMClock instantly reboots the system.

Also, I cannot understand why anything lower than 1.2 set in BIOS (at 2.1GHz) causes problems. I cannot even start Windows, at 1.15V I hardly could go back to BIOS config after several restarts). However, setting 1.2V in BIOS and further undervolting with RMClock works great. Anyone else seeing this? The board is Asus M2A-VM HDMI , BIOS 0703

The same board (M2A-VM HDMI) tested with all avalable bios revisions.

With X2 3600 brisbane stock speed 1.9GHz at 0.975 bios OR rmclock.
At 5x200=1GHz with RMClock ok at 0,825, but i cant boot from bios with less than 0,875 at the same speed.

****WARNING****!
When voltage is NOT set "AUTO" in BIOS you CAN'T change within windows based applications! I also did some tests my first hours with this board getting some wide smiles, but monitoring vcore with everest you can see that if a voltage is selected in BIOS you can't change it in windows. RMClock monitor shows that it is as you set it, but it is ALWAYS as set in BIOS!
For example if set 1.2V in BIOS as you have done, no matter what you will do in RMClock the vcore is always 1.2!

(the same happens with multiplier)

floffe · Post by **floffe** » Sat Sep 15, 2007 2:14 pm

An old one:
Athlon XP 2500+ Barton (1.83GHz)
1870MHz (11*170) @ 1.375V (stock 1.60V)

Will post again when I can undervolt my Pentium M Banias in software. There are quite a few Pentium M undervolting results here too.

kike_1974 · Post by **kike_1974** » Tue Sep 18, 2007 6:58 am

My computers, all of them 24h orthos-stable:

Athlon64 3000+ Clawhammer (2.0GHz) 89W TDP
Minimun: 800MHz (4*200) @ 0,825V (stock 1GHz @ 1.1V with C&Q))
Stock: 2GHz (10*200) @ 1,375V (stock 2GHz @ 1,5V)

Athlon64 3000+ Winchester (1.8GHz) 62W TDP
Minimun: 1GHz (5*200) @ 1,1V (stock 1GHz @ 1,1V with C&Q) - Note: lowest possible VID
Stock: 1,8GHz (9x200) @ 1,175V (stock 1,8GHz @ 1,4V)

Pentium M 2.0GHz 35W TDP
Minimun: 800MHz (6*133) @ 0,7V - Note: lowest possible VID
Stock: 2GHz (15*133) @ 1,068V (stock 2GHz @ 1,356V)

Athlon X2 4600+ Manchester (2,4GHz) 75W TDP
Minimun: 1GHz (5*200) @ 1,1V (stock 1GHz @ 1,1V with C&Q) - Note: lowest possible VID
Stock: 2,4GHz (12*200) @ 1,225V (stock 2,4GHz @ 1,350V)

Athlon X2 4800+ Brisbane (2,5GHz) 65W TDP
Minimun: 1GHz (5*200) @ 0,8V (stock 1GHz @ 1V with C&Q) - Note: lowest possible VID
Stock: 2,5GHz (12,5*200) @ 1,2V (stock 2,5GHz @ 1,225V)

C2D E6600 Conroe (2,4GHz) 65W TDP
Minimun: 1,6GHz (6*266) @ 1,136V (stock 1,6GHz @ 1,136V with speedstep) - Note: lowest possible VID
Stock: 2,4GHz (9*266) @ 1,136V (stock 2,4GHz @ 1,340V)
OC'd: 2,760GHz (8*345) @ 1,136V (notes: same voltaje as with speedstep at this frequency!!)
OC'd: 3,1GHz (9*345) @ 1,340V (notes: overclocked to maximun stock voltaje)

darkbulb · Post by **darkbulb** » Fri Sep 21, 2007 6:47 am

papakoo wrote: ****WARNING****!
When voltage is NOT set "AUTO" in BIOS you CAN'T change within windows based applications! I also did some tests my first hours with this board getting some wide smiles, but monitoring vcore with everest you can see that if a voltage is selected in BIOS you can't change it in windows. RMClock monitor shows that it is as you set it, but it is ALWAYS as set in BIOS!
For example if set 1.2V in BIOS as you have done, no matter what you will do in RMClock the vcore is always 1.2!
(the same happens with multiplier)

Are you sure about this? I could swear I saw the lower voltage in Speedfan and PCProbe, but I don't quite remember now how it was set in BIOS . I will try again this weekend.
Anyway, my question stays: why does it go lower(and perfectly stable) when set by RMClock compared to setting in BIOS (1.031V vs 1.181V IIRC)
Additional question: what BIOS version are you using?

loimlo · Post by **loimlo** » Fri Sep 21, 2007 10:45 am

AMD Athlon 64 3000+ - Orleans (AM2, Revision F2) 59W TDP
Minimum: 1Ghz @ 0.825V
Stock: 1.8G @ 1.1V

I am pretty satisfied with result, enough for downloading.

Icharus · Post by **Icharus** » Sun Sep 23, 2007 12:52 am

Pentium M Banais 1.4GHz

600MHz @ 0.700V
1400MHz @ 1.100V

stock: 1.4GHz @ 1.484V

This has gained me an extra 45 mins of battery time, which I am very happy about.

Mikael · Post by **Mikael** » Sun Sep 23, 2007 1:48 am

Okay, I just got to test the E2160 in the Gigabyte board for a short time. I never found the absolute minimum, but it did manage to run stable at 2.4GHz and 1.08V. Pretty good. Although I never found the minimum, I'm certain that I wouldn't be able to go much lower than that.

Mikity · Post by **Mikity** » Mon Sep 24, 2007 10:28 am

Palindroman wrote: AMD Opteron 185 - Denmark (939) stock - 1.35V

Minimum: 0.8 Ghz @ 0.800 Volt
Stock: 2.6 Ghz @ 1.200 Volt

Where did these figures come from? Couldn't find them anywhere in this thread. For what it's worth, I can run Orthos for over an hour at 1.0GHz/0.8V and 2.6GHz/1.125V. Using a XP-90 with Noiseblocker UltraSilent SE2 92mm (controlled via BIOS).
Or how long should I be running Orthos for to be sure?

Cheers, Mikity

FlorisNielssen · Post by **FlorisNielssen** » Tue Sep 25, 2007 12:45 am

Best should be 24h. But at least 12 I suppose.

mrinsane19 · Post by **mrinsane19** » Wed Oct 03, 2007 12:28 am

Ok... stupid question coming up... but how do I stress all cores?

Orthos can do 0 & 1, I can set Prime95 to do 2... but what can I use to stress 3? I can only seem to load 1 instance of Prime93. Never mind, found the switch : P Will post back with results later.

Oh and Q6600 B3 stock VCore 1.3125.... and heading south :p

mrinsane19 · Post by **mrinsane19** » Wed Oct 03, 2007 3:29 am

Intel Core 2 Quad Q6600 Kentsfield (Rev B3, Stepping 7) 105W TDP

Stock: 2.4GHz 1.31250V Temps 70.0/51.0 (1.6GHz speedstep)C
Minimum: 2.4GHz 1.16875V Temps 62.8/48 (1.6GHz speedstep).0C

This was the minimum VID allowed on this CPU and is short test stable with 1x Orthos 2x Prime95. Will test overnight/tomorrow for long term stability but I'd be shocked if it failed. RMClock allowed 1.162V but CPU-Z reported the same VCore so I suspect 1.16875V is the floor. Update Intel indicate minimum VCore of 1.100V, CPU-Z is currently reading 1.120V unloaded (drops to 1.088V with 4core load) so that really really really is as low as it's going - damn!

I assume the reduction in temp change from idle/load is the fact that there's no voltage change, whereas before it made that jump from 1.16875 to 1.31250 - the temp change is purely frequency based.

I am happy with a 7C reduction for a couple of hours work and exactly $0 spent

Palindroman · Post by **Palindroman** » Sat Oct 13, 2007 6:04 am

I've finally come round to include everyone's recent entries. With results from more than 40 CPUs things are taking shape. Thanks, Mikael, scaryduck, ddrueding1, papakoo, Steve Teixera (3 entries), mimwdv, ryboto, FlorisNielssen, darkbulb, Flandry (for the Tuluatin

), floffe, loimlo, Icharus, mrinsane19. Special thanks go out kike_1974 for entering the 'voltajes' of six of his CPUs.

ps Added the LE-1100 myself.

AMD Sempron LE-1100 - Sparta (AM2) stock - 1.35V

Minimum: 0.8 Ghz @ 0.800 Volt
Stock: 1.9 Ghz @ 0.950 Volt (12 hrs Orthos)

RedAE102 · Post by **RedAE102** » Sun Oct 14, 2007 1:04 am

papakoo wrote:
With X2 3600 brisbane stock speed 1.9GHz at 0.975 bios OR rmclock.
At 5x200=1GHz with RMClock ok at 0,825, but i cant boot from bios with less than 0,875 at the same speed.

Just out of curiosity, do you know what the default voltage of your Brisbane 3600+ is? I ask because my default is 1.30 V and I can't get it stable below 1.000 V at full speed. I've heard that Brisbanes come with 1.25 V, 1.30 V, and 1.35 V default voltages depending upon the individual processor. But anyway, here goes...

AMD Athlon X2 3600+ - Brisbane (AM2) stock - 1.30 V

Minimum: 1.0 GHz @ 0.825 V
Stock: 1.9 GHz @ 1.000 V

P-states for CrystalCPUID:
O/C Min: 1.138 GHz @ 0.850 V
O/C Mid: 1.771 GHz @ 0.975 V
O/C Max: 2.403 GHz @ 1.175 V

StApostol · Post by **StApostol** » Sun Oct 14, 2007 1:40 am

S939 Athlon64 3200+ (Venice):

* 1.1V between 1GHz-1.75GHz (minimum voltage)
* 1.125V at 2GHz (wrote 1.175V before - oops!)
* 1.275V at 2.25GHz (overclocked)
* 1.425V at 2.5GHz (overclocked, overvolted)

Stock is 1.4V at 2GHz. Many multipliers in this CPU (4x-10x), and excellent idle power consumption when undervolted. I will turn it into a silent (1 fan) server-in-a-closet.

S775 Core 2 Duo E6750:

* 1.187V between 2.0GHz-2.66GHz (minimum voltage)
* 1.212V at 2.8GHz (overclocked)
* 1.325V at 3.2GHz (overclocked)

Stock is 1.35V at 2.66GHz. Only three multipliers (6x-8x), and idle power consumption is much higher than the Athlon64 (I'd say about 20-30W judging from the PSU fan). Very fast though.

On a sidenote, does anyone know of a program that can change FSB and CPU voltage according to system load, on a Gigabyte P35-DS3? I'd like to bring power consumption down a little, while still maintaining overclocking potential.

Right now, I'm using RMClock to control the multipliers and VCore of the CPU, but it cannot affect voltage directly (to go below the 1.187V minimum VCore). Clockgen can change FSB, but doesn't monitor system load. Gigabyte's Easytune can change both FSB and CPU Voltage, but doesn't monitor system load either. Speedfan doesn't recognize the clock generator, and can't control voltages...

If worse comes to worst, I could write a script to monitor system load and use Easytune to do it's magic, but this is rather cumbersome. It would be better if there is an open source program, for example, that I could modify to add support for this motherboard.

Palindroman · Post by **Palindroman** » Sun Oct 14, 2007 2:37 am

Thanks for the entries, RedAE102 and St.Apostol!

StApostol wrote:
On a sidenote, does anyone know of a program that can change FSB and CPU voltage according to system load, on a Gigabyte P35-DS3? I'd like to bring power consumption down a little, while still maintaining overclocking potential.

Wasn't CrystalCPUID a good tool for this? I vaguely remember smilingcrow once mentioning it allowed you to undervolt as well as overclock your CPU dynamically.

StApostol · Post by **StApostol** » Sun Oct 14, 2007 3:41 am

Palindroman wrote:Thanks for the entries, RedAE102 and St.Apostol!

StApostol wrote:
On a sidenote, does anyone know of a program that can change FSB and CPU voltage according to system load, on a Gigabyte P35-DS3? I'd like to bring power consumption down a little, while still maintaining overclocking potential.
Wasn't CrystalCPUID a good tool for this? I vaguely remember smilingcrow once mentioning it allowed you to undervolt as well as overclock your CPU dynamically.

Unfortunately, it can only change the CPU multipliers and VCore (like RMClock). While this is perfectly fine for Athlons and mobile processors, the E6750 only has three multipliers and its lowest VCore is a rather high 1.187V, which limits underclocking/unervolting potential. You can overcome this by interacting with the motherboard, but so far I don't know any such program that is versatile enough for real-time control.

Edit: I checked again and sure enough, my Athlon64 was set to 1.125V at 2.0GHz, not 1.175V that I wrote. You may wish to update the OP with this

Palindroman · Post by **Palindroman** » Sun Oct 14, 2007 5:36 am

StApostol wrote:
Edit: I checked again and sure enough, my Athlon64 was set to 1.125V at 1.125V, not 1.175V that I wrote. You may wish to update the OP with this

Yes, I wondered about that one, since I have a 3200+ Venice in my workstation myself.

jackylman · Post by **jackylman** » Sun Oct 14, 2007 7:38 am

The Brisbanes are impressive. I'll be stress-testing my 4800 Brizzy this week now that I've figured out how to undervolt below the defaults with Ubuntu.

Thanks to those Brizzy owners who've posted their results. This time, I have some guidelines. The last time I did this, with the Orleans core, it had just come out and most people buying AM2 were getting Windsors. I felt so alone

ST · Post by ST » Wed Oct 31, 2007 1:28 pm

s939 Opty 165

P-Min State = 800Mhz @ .850V
P-Mid State = 2.0GHz @ .995V
P-Max State = 2.4GHz @ 1.125V

I can overclock to 2.8GHz @ stock 1.35V and even 3.0GHz Dual Prime 95 Stable, but that requires ~ 1.475V. Since I don't play FPS anymore, the above P-States are my typical setups.

fyi - i had a write up about overlclocking / undervolting about a year back :

viewtopic.php?t=30703&highlight=rmclock

TheZeroorez · Post by **TheZeroorez** » Wed Oct 31, 2007 1:59 pm

Intel E6320 @ 2,8GHz >> 1,2675v in the BIOS, about 1,216v CPUz readout on full stress.

10h Orthos prio 9 stable.

Oh, and it's under an Arctic Freezer 7 Pro. With all my fans at 5v and the Freezer slow it's about 32 degrees idle and 39 stressed, this is when my room temp is 19 degrees (celcuis).

miahallen · Post by **miahallen** » Sat Nov 03, 2007 11:11 pm

Just thought I'd add my new Q6600 G0, it's a beauty for UVing. Runs completely stable at stock speeds with only 1.0375V (stock @ 1.35V). I tried going lower (speed & voltage) without success. She'll clock a bit lower, but any less voltage, and the rig won't boot.

I also OCed to 3.0GHz with a mild UV to 1.285V! Not too shabby!

Both these results were 8hrs+ ORTHOS & RTHDRBL stable.

Techno Pride · Post by **Techno Pride** » Sun Nov 04, 2007 12:23 am

AMD Athlon X2 3600+ - Windsor (AM2) stock - 1.25V

Minimum: 1 GHz @ 0.900 V
Stock: 2.0 GHz @ 1.075v

mrinsane19 · Post by **mrinsane19** » Sun Nov 04, 2007 3:20 am

StApostol wrote:S939 Athlon64 3200+ (Venice):

S775 Core 2 Duo E6750:

* 1.187V between 2.0GHz-2.66GHz (minimum voltage)
* 1.212V at 2.8GHz (overclocked)
* 1.325V at 3.2GHz (overclocked)
On a sidenote, does anyone know of a program that can change FSB and CPU voltage according to system load, on a Gigabyte P35-DS3? I'd like to bring power consumption down a little, while still maintaining overclocking potential.

I think you'll struggle, I'm pretty sure the board itself won't allow you to go below the minimum VID. Read my post above, BIOS undervolting on a P35-DS3 I found that I probably could go lower but the mobo itself wouldn't supply anything below minimum VID (regardless of the BIOS setting). Damn Intel

LickMe · Post by **LickMe** » Mon Nov 05, 2007 8:59 am

AMD Mobile Barton 2500+ (1.45v)

At stock speed (1.83Ghz) I run it at 1.360v.

Underclocked to 1.5ghz, I run it at 1.200v without any problems whatsoever. I've gone as low as 1.1v, but that does give problems under load. I found that anywhere between 1.2 and 1.25 gives the best results at this speed.

Esben · Post by **Esben** » Sun Nov 11, 2007 11:53 am

I recently aqquired a Brisbane 4800+ Rev G2, which run at these multipliers and voltages:

4 0.8 (800 MHz HT bus)
5 0.8
6 0.825
7 0.85
8 0.9
9 0.95
10 1.0
11 1.050
12 1.1

Though I cannot achieve stability at transitions when running less than 1.0v. Does anyone else have problems getting their system to transition from 0.8v to 1.x v at transitions?

Copper · Post by **Copper** » Wed Nov 14, 2007 7:54 pm

Pentium M Dothan 1.8 GHz

0.6 GHz @ 0.716 Vcore
1.4 GHz @ 0.908 Vcore (~5 watts running CPU Burn)

Undervolting: how low can you go?

Re: undervolting: how low can you go?