Undervolting: how low can you go?

farfromuman · Post by **farfromuman** » Fri Dec 19, 2008 11:38 am

My CrystalCPU settings for Athlon X2 5400+ BE 1.35v

2.8ghz 1.2v 122W/155W
2.0ghz .950v 102W/115W
1.2ghz .800v 91W/97W

The power numbers are under idle/load. My motherboard overvolts by ~.025v or at least that is what shows in speedfan.

It will run at 3Ghz/1.275v/175Watts but it is just too much heat for my small case.

Small edit, I removed my ATI HDTV wonder PCI card and installed a USB HD tuner - power usage went down 10W. Maybe I need to swap my HVR-1600 PCI tuner for USB as well. I wonder how efficient the PS is.

yamahaSHO · Post by **yamahaSHO** » Fri Dec 19, 2008 12:36 pm

I have my Q9300 overclocked at 3Ghz while undervolting it to 1.032v.

ryboto · Post by **ryboto** » Fri Dec 19, 2008 6:19 pm

yamahaSHO wrote:I have my Q9300 overclocked at 3Ghz while undervolting it to 1.032v.

I have a Q9400, and I can't even get it near 3.0ghz without more than 1.2v....maybe it's my power supply.

Ksanderash · Post by **Ksanderash** » Sat Dec 20, 2008 2:24 am

ryboto wrote:I have a Q9400, and I can't even get it near 3.0ghz without more than 1.2v....maybe it's my power supply.

Or, what is more likely, VRM power design. Or just a bad crystal.

DeDeRa · Post by **DeDeRa** » Sun Dec 21, 2008 12:04 am

Intel E8400:

oc @ 3600 : 1.160v
stock @ 3000 : 1.008v
... @ 2000 : 0.925v

DeDeRa · Post by **DeDeRa** » Sun Dec 21, 2008 12:04 am

DeDeRa wrote:Intel E8400:

oc @ 3600 : 1.160v
stock @ 3000 : 1.008v
... @ 2000 : 0.925v

ps: Bios V, not CPU-Z

yamahaSHO · Post by **yamahaSHO** » Sun Dec 21, 2008 5:23 pm

ryboto wrote:
yamahaSHO wrote:I have my Q9300 overclocked at 3Ghz while undervolting it to 1.032v.
I have a Q9400, and I can't even get it near 3.0ghz without more than 1.2v....maybe it's my power supply.

I've been pretty lucky with this chip. I have the NB and SB set at 'Auto' on a P5Q-E. I bought this board after reading reviews on it being a fairly stable motherboard.

I haven't tried to OC any more and that was the lowest voltage I could get with 3Ghz. I haven't tried to see how low it could go at stock speed.

ryboto · Post by **ryboto** » Mon Dec 22, 2008 5:50 am

Ksanderash wrote:
ryboto wrote:I have a Q9400, and I can't even get it near 3.0ghz without more than 1.2v....maybe it's my power supply.
Or, what is more likely, VRM power design. Or just a bad crystal.

Well, I've tried 3 different motherboards, all wouldn't let me OC to 3.0ghz with a bump in FSB at stock vcore. I've since changed the RAM, from 4x1gb to 2x2gb, and I haven't tried since then. The P45/G45 seemed to have issues doing anything above stock, or even booting on some boards if all 4 banks are used, at least that's what I encountered. Haven't had time to play with it. It's either the RAM, or the power.

ex.treme · Post by **ex.treme** » Wed Dec 31, 2008 9:52 am

E5200 @2,5 Ghz (stock) @0.9250v at bios. Cpuz shows 0.880v.
Looks stable. I need more testing.
0.950v is stable.

QuietOC · Post by **QuietOC** » Wed Dec 31, 2008 10:46 am

ex.treme wrote:E5200 @2,5 Ghz (stock) @0.9250v at bios. Cpuz shows 0.880v.
Looks stable. I need more testing.
0.950v is stable.

Very interesting. I haven't been able to undervolt my E5200 at all beyond the normal EIST setting.

plympton · Post by **plympton** » Wed Dec 31, 2008 11:07 am

My CrystalCPU settings for Athlon X2 5400+ BE 1.35v

3.0ghz 1.275v 90W idle 141W load
2.0ghz 1.100v 82W idle 109W load
1.0ghz 0.800v 75W idle 83W load

These numbers are measured with a Kill-a-watt and visually averaged after a few seconds of stability from Prime95 2-core.

The MB is an Asus M2NPV-VM, with a Radeon 3450, GP 1 TB (original) drive, 3 GB mem, and a Neo 430 HE PS (that doesn't like to boot sometimes).

-Dan

ryboto · Post by **ryboto** » Fri Jan 02, 2009 12:26 pm

plympton wrote:My CrystalCPU settings for Athlon X2 5400+ BE 1.35v

3.0ghz 1.275v 90W idle 141W load
2.0ghz 1.100v 82W idle 109W load
1.0ghz 0.800v 75W idle 83W load

These numbers are measured with a Kill-a-watt and visually averaged after a few seconds of stability from Prime95 2-core.

The MB is an Asus M2NPV-VM, with a Radeon 3450, GP 1 TB (original) drive, 3 GB mem, and a Neo 430 HE PS (that doesn't like to boot sometimes).

-Dan

See, yours also seems high, like mine....at 1.0ghz and 0.8v, that chip is going to be sub-30W, maybe much less then that. A 3450 uses like nothing, and a single hard drive is ~5W. So, maybe our boards are eating a lot of power(both Asus), or our power supplies aren't suited for such low power systems?

plympton · Post by **plympton** » Fri Jan 02, 2009 12:32 pm

ryboto wrote:
plympton wrote:My CrystalCPU settings for Athlon X2 5400+ BE 1.35v

3.0ghz 1.275v 90W idle 141W load
2.0ghz 1.100v 82W idle 109W load
1.0ghz 0.800v 75W idle 83W load

These numbers are measured with a Kill-a-watt and visually averaged after a few seconds of stability from Prime95 2-core.

The MB is an Asus M2NPV-VM, with a Radeon 3450, GP 1 TB (original) drive, 3 GB mem, and a Neo 430 HE PS (that doesn't like to boot sometimes).
See, yours also seems high, like mine....at 1.0ghz and 0.8v, that chip is going to be sub-30W, maybe much less then that. A 3450 uses like nothing, and a single hard drive is ~5W. So, maybe our boards are eating a lot of power(both Asus), or our power supplies aren't suited for such low power systems?

My 3450 uses 20 watts at idle! :-/. I pulled it out and just used the on-board 6150 chip to confirm it. Ick. I don't think mine throttles down or does PowerPlay too well.

That, and I think the nVidia MB I'm using is a bit of a power hog compared to new ones - though a swap would take like 20 years (well, maybe a few less) to pay for itself in savings, so I won't do it.

-Dan

Ksanderash · Post by **Ksanderash** » Sat Jan 03, 2009 10:03 am

QuietOC wrote:
ex.treme wrote:E5200 @2,5 Ghz (stock) @0.9250v at bios. Cpuz shows 0.880v.
Looks stable. I need more testing.
0.950v is stable.
Very interesting. I haven't been able to undervolt my E5200 at all beyond the normal EIST setting.

Have you tried VID change via scotch tape applied to the pads of CPU? I did right this way for 0,925V. Had only one contact to be isolated.

ex.treme · Post by **ex.treme** » Sat Jan 03, 2009 10:21 am

QuietOC wrote: Very interesting. I haven't been able to undervolt my E5200 at all beyond the normal EIST setting.

Hi!
Eist and C1E enabled at bios. Everything works fine.

Ksanderash: No i didn't tried.
I just set with bios 0.9250v and works fine.

rsa · Post by **rsa** » Sun Jan 18, 2009 9:44 am

AMD Phenom X4 9950 BE, 780G, $8 PSU

Stock:

C'n'Q (6.5x, 1.3GHz, 1.05v): 156 Watts
Load (13x, 2.6GHz, 1.30v): 279 Watts

5x, 1GHz, 0.8v:

Idle: 81 Watts
Load: 97 Watts

lowpowercomputing · Post by **lowpowercomputing** » Thu Jan 29, 2009 11:54 am

AMD Athlon LE-1640 â€“ Lima (AM2)/65nm/G2 â€“ stock: 1.25V

Minimum..........1.0 GHz @ 0.760 V
Stock...............2.7 GHz @ 1.104 V
Overclock.........3.0 GHz @ 1.208 V

It's a shame they disabled 4x so I can't test at 800 MHz.

Lostfaith · Post by **Lostfaith** » Thu Jan 29, 2009 8:14 pm

Anyone with a phenom Deneb with the lowest vcores for 2Ghz and 3 ghz?

ex.treme · Post by **ex.treme** » Tue Feb 03, 2009 12:26 pm

Not good like Y-3, but closer

[email protected] @0.7250v in bios, Cpuz shows 0.688v, core temp at idle shows 30Â°C , super pri 41s. Consumption Idle- 40w

Mariner · Post by **Mariner** » Fri Feb 06, 2009 9:51 am

After upgrading to a newer motherboard, I've finally found the impetus to look at undervolting. My CPU is an old Athlon X2 3600+ (Brisbane running at 1.9GHz stock) and, in my old motherboard, I was simply undervolting to 1.0V at the stock 1.9GHz clock.

My new motherboard is an Asus M3N78-VM which, I was rather nonplussed to find, doesn't support undervolting in the BIOS. That'll teach me not to do my research properly before buying!

The lack of BIOS undervolting has led me to take a look at using Crystal CPUID and I'm now running with the following settings:

1.0GHz @ 0.8V (Speedfan: 0.85V) (Edit: 40W idle/43W load)
1.4GHz @ 0.825V (Speedfan: 0.88V) (Edit: 44W idle/48W load)
1.9GHz @ 0.95V (Speedfan: 1.0V) (Edit: 50W idle/58W load)

You'll note that Speedfan reports a higher voltage than CCPUID and, as far as I can tell, this is because the bloody stupid motherboard BIOS automatically enables an 'overclock' mode and bumps up the voltage by 0.05V without providing any option to disable this setting! Aaargh!!

Not really too much of a problem but it means that I'm not able to test 1.0GHz at a lower effective voltage than 0.85V as reported by Speedfan. I'm guessing the CPU would be capable of 1.0GHz @ 0.8V but can't currently select this option.

Other than the ridiculous BIOS limitations, the motherboard itself seems to be a pretty good one which was also decent value. I'll test power consumption if I get the opportunity to do so and will amend this post as necessary.

Edit:

I've just installed a PicoPSU 150XT because the original power supply has been causing problems. This new PSU is obviously more efficient than the old 19V PSU which came built into the case as I'm seeing a reduction in power draw of between 5-7W.

Here are the new figures:

1.0GHz @ 0.8V (Speedfan: 0.85V) (35W idle/37W load)
1.4GHz @ 0.825V (Speedfan: 0.88V) (37W idle/42W load)
1.9GHz @ 0.95V (Speedfan: 1.0V) (44W idle/51W load)

farfromuman · Post by **farfromuman** » Fri Feb 06, 2009 10:22 am

Mariner wrote:
Not really too much of a problem but it means that I'm not able to test 1.0GHz at a lower effective voltage than 0.85V as reported by Speedfan. I'm guessing the CPU would be capable of 1.0GHz @ 0.8V but can't currently select this option.

There is a .775V setting in CrystalCPU, you need to edit the ini file and change "V30" = .8V to "V31" = .775V or create a shortcut at .8V and edit the switch.

Mariner · Post by **Mariner** » Fri Feb 06, 2009 2:57 pm

I tried the INI edit you mention but no option for lower than 0.8V appeared in CCPUID. I've a feeling this might be because my Brisbane is a relatively early revision which doesn't support voltages below 0.8V. *shrugs*

I'm not too worried about that though because I've just discovered this poxy motherboard doesn't support wake on USB from S3 suspend which kind of screws up my plans for the system! I'm sure I read a spec sheet somewhere indicating this was supported. Looks as though I may end up looking for a new motherboard with this capability and just try and flog this one on eBay.

Edit: Bizarrely enough, this motherboard seems to allow wake on USB after all, despite not actively supporting it in either hardware or the BIOS.

Unfortunately, I'll have to get rid of it in any case as it exhibits audible coil whining at 1.9GHz and to a lesser degree at 1.4GHz. My previous motherboard exhibited no such problem running at the same speed and voltage. Asus M3N78-VM - not recommended for silent PCs!

alfhenrik · Post by **alfhenrik** » Sat Feb 28, 2009 5:51 am

E6400, Stepping L2, running at stock speeds with EIST enabled (going between 1.6 and 2.13Ghz) 0.975 (BIOS), 0.944 (Windows) Gigbabyte DS3P, Orthos stable for 8 1/2 hours now..any lower than that and Orthos fails after a couple of minutes (~0.95v) / seconds (0.90v).

Esben · Post by **Esben** » Tue Mar 03, 2009 4:21 am

My brothers new quad core build:

Gigabyte GA-MA78GM-S2H
Phenom X4 9650 DR-B3
2x2 GB DDR2
ATI Radeon HD 2600 XT
WD Green 1 TB
M-Audio Delta 410
Corsair HX520 PSU

CPU runs at 2300 MHz at load, and 1150 MHz at idle.
Default voltage is 1.2v, which gives a idle wattage of 106W (Linux) and 112W (Windows). 4xPrime in Windows is 179W.

Lowest stable voltage is 1.075v. Idle wattage 104W (Linux) and 106W (Windows). 4xPrime in Windows is 156W.

Power savings when undervolted, 6W idle, 23W load.

RedAE102 · Post by **RedAE102** » Tue Mar 03, 2009 4:11 pm

On behalf of my friend with an original stepping C2D E8400, I'd like to post his results:

System Specs
Intel Core 2 Duo E8400, Wolfdale C0
Stock 3.0 GHz @ BIOS VID: 1.1125V
Everest observed: 1.07V

Gigabyte GA-E7AUM-DS2H w/ integrated GeForce 9400 graphics, Stock clocks 580/1400 MHz (GPU/shader), overclocked to 674/1624 MHz
2x2 GB G.Skill Pi Black DDR2-800 RAM, 5-4-4-12 @ 1.84V (not CAS4 due to BIOS bug that still hasn't been remedied)
Hard Drives: WD3000BLFS 300GB VelociRaptor, Hitachi P7K500 500GB
AverMedia MCE A180 PCI HDTV (ATSC) Tuner
PicoPSU 120 with EDAC 110W brick
Antec SLK3800BQE with 2x120mm Scythe Gentle Typhoon (1450 rpm model) @ 9V, 1x80mm Nexus Fan @ 7V using part of the carcass of the deceased stock PSU
Xigmatek HDT-D1264 top-down CPU cooler with Scythe Kama PWM 120mm fan.
Windows Vista Ultimate x64 SP1

58-59W idle, 98W peak observed running GTA4. He allows Speedstep to do its thing and drop idle speed and voltage. I didn't get numbers on that part, but the idle voltage also drops proportionately to the drop in the BIOS voltage. When playing GTA4, the screaming fan in the 110W brick comes on and stays on until power consumption drops. Also comes on for a few seconds at boot.

NickH · Post by **NickH** » Thu Mar 05, 2009 2:24 pm

Has anyone got any figures for the AMD Athlon X2 5050e?

PASware · Post by **PASware** » Sat Mar 07, 2009 5:04 am

I have tried a BeQuiet 300w 80+ with the following system:

X2 3600+ (1,8GHz 1,1v & idle 1GHz 0,9v)
Asrock ALiveNF6P-VSTA
1GB DDR2
40GB Hitachi 2.5" laptop HDD
BeQuit Purepower 300W
Voltcraft Energy Check 3000

Idle: 21w (~23.5w with boxed cpu fan)
Load: 48w

Who needs a PicoPsu anyway?

Lostfaith · Post by **Lostfaith** » Sun Mar 08, 2009 11:04 pm

Phenom II 940
4x1gb OCZ 1066 SLIRdy ram
GA Ma790GX-DS4H
BFG maxcore GF 260 GTX 55nm
2x500GB WD SE16mb Caviars
1x 320GB Seagate
FSP 700GLN PSU
optical liteon with a Vista disk in it (bootmanager from vista is screwy)
Logitech quickcam orbit webcam

With K10stat:
3200MHz @ 1.296 Vcore
2400MHz @ 1.056 Vcore
1600MHz @ 0.896 Vcore
800 MHz @ 0.736 Vcore

My APC ES-750 UPS reports:
99Watt idle (wattage includes active 22" acer AL2216Wbd, Logitech 5.1 Z-5300e, A Dlink DI-524 router and an adsl modem)

Load: 248Watt OCCT & fullscreen RThdribl

Load: 198Watt OCCT only

roomtemp: ~28 degrees (caribbean)

temps etc, see screenshot

bottom · Post by **bottom** » Mon Mar 09, 2009 4:58 am

@Lostfaith
sounds really nice !!!
could you please also post values without the display etc ?

thx!!!

bottom

bhvm · Post by **bhvm** » Sun Mar 29, 2009 1:39 am

Very informative Thread

Here's Mine finding

System- HP DV8000, 17 inch display, 2X Seagate 7200 RPM in RAID0, Nvidia SLi
Processor- Intel C2D Mobile T2300 - Yonah (479) stock

Tool- RMC (performance on demand)

Minumum- 1.0Ghz @ 0.95v to1.5 Ghz @ 0.95v

Full speed 1.66 Ghz @ 0.96V

This processor Runs ALL multipliers except top speed at 0.95v!!
Default Stock voltage was 1.262v

Undercolcking boosted my battery life 20min and dropped the temps by 30.C!!!

Undervolting: how low can you go?

Athlon X2 5400+ Black Edition

Re: Athlon X2 5400+ Black Edition

Re: Athlon X2 5400+ Black Edition

thanks