Undevolt ATI 38xx videocards!

plympton · Post by **plympton** » Tue Feb 05, 2008 3:14 pm

Not sure if anyone caught this yet, but there's a way to underclock, and underVOLT the 38xx series of video cards directly in the BIOS. If you sent your region to German (for the "." and "," swap) it will worok for the voltages (otherwise an extra "bit" gets written to the BIOS file and corrupts it).

I confirm that it worked with my Visiotek 3850 last night - it would clock the chip and the memory to 300/400 MHz respectively, and you can change the 2d and 3d modes, too.

Unforunately, it didn't do much for my hackintosh high videocard temps.. oh well...

http://www.aledander.de/vb/ati_bios_edi ... osedit.zip

-Dan

KansaKilla · Post by **KansaKilla** » Tue Feb 05, 2008 8:42 pm

That is a great tip, Dan, and it'll be interesting to see what happens to my Visiontek 3850. Thanks for the info. Too bad about your "hackintosh" temps, though.

plympton · Post by **plympton** » Wed Feb 06, 2008 8:27 am

KansaKilla wrote:That is a great tip, Dan, and it'll be interesting to see what happens to my Visiontek 3850. Thanks for the info. Too bad about your "hackintosh" temps, though.

Well, it IS a hack, after all.

I'm really curious what PowerPlay IS, if it's not just dynamically scaling the clock speeds. From the program, it appears that there's 4 "states" to PowerPlay, and they all revolve around Memory and GPU clock speeds and voltages. You can set them with the program in BIOS, and whatever software available should set them.

I wonder if it also involves a "nap" mode like they have for CPU's now ("enhanced Halt State"?)

I've yet to pop my power meter on the rig to see what it's sipping compared to the 950 on-board graphics...

-Dan

ryboto · Post by **ryboto** » Wed Feb 06, 2008 9:08 am

supposedly, the next release of Atitool will be able to undervolt through software. It's going to be like the CrystalCPUID for GPUs!

Vicotnik · Post by **Vicotnik** » Sun Feb 17, 2008 9:28 pm

I've been playing around with ComputerBase ATi BIOS-Editor 0.91 Beta for a while and managed to shave a few watts off my idle power consumption.

A few useful URLs
- http://www.xtremesystems.org/forums/sho ... p?t=175531
- http://www.computerbase.de/downloads/tr ... os-editor/
- http://www.techpowerup.com/vgabios

kike_1974 · Post by **kike_1974** » Mon Feb 18, 2008 6:57 am

Vicotnik wrote:I've been playing around with ComputerBase ATi BIOS-Editor 0.91 Beta for a while and managed to shave a few watts off my idle power consumption.

A few useful URLs
- http://www.xtremesystems.org/forums/sho ... p?t=175531
- http://www.computerbase.de/downloads/tr ... os-editor/
- http://www.techpowerup.com/vgabios

What stable voltages and frequencies are you using for 2D and 3D?

Vicotnik · Post by **Vicotnik** » Mon Feb 18, 2008 7:48 am

Right now I have just changed the 2D Clock Vcore from 1.241v to 0.974v according to the BIOS editor; I have not confirmed the Vcore using a multimeter or anything like that.

Seems to drop idle power consumption by a few watts. I also tried 0.9v (lowest setting in the BIOS editor) but I think that actually raised the power consumption. Hard to tell really, my power meter is not very good or at least not sensitive enough for such small changes.

I have not touched Vcore for the 3D modes yet.

davidh44 · Post by **davidh44** » Mon Sep 15, 2008 1:17 am

Interesting! My friend has an Asus HD3450 card that doesn't support Powerplay even though the chip does. This essentially lets you enable Powerplay with your choice of voltages, right?

digaderfox · Post by **digaderfox** » Wed Sep 24, 2008 1:38 pm

Hi dudes,

I need to ask you for some help because I run into an issue that totally puzzles me.

I bought two days ago two Connect3D 4670 512 (for a multiscreen setup).

I was disapointed by the noise of the fan as soon as I kicked it in. So I decided to run to the store and get two Accelero S1 rev2.

As for the mounting job, nothing special. Oh yes : there is a coil and a condenser that slightly touch the cooler in the right upper corner. Nothing bad : some tape to ensure isolation does a great job.

This is now thing goes wrong.
The idle temperature is at 34Â°.
While burning with Atitool, each time the temperature would reach 45Â° or so and Windows will reboot (Vista64). And each try is the same. It would never goes higher than 50Â°.

I tried with the two cards and results are the same.

So I rolled back to the little turbine. It is now running for half an hour without trouble.

I really can't understand what I'm missing.

It's cooler with Accelero but will hang with no reason ?

Could there be some kind of protection in the bios that makes it impossible for the card to run without a fan ? (I'll test the mixed solution)

Any advice would be appreciated.

alecmg · Post by **alecmg** » Wed Sep 24, 2008 1:49 pm

Insufficient cooling to memory or VRM perhaps?

digaderfox · Post by **digaderfox** » Wed Sep 24, 2008 9:36 pm

Damn. The silly clic issue...

I intended to post my question in this topic.

Btw, any help would be appreciated.

To ensure this wasn't dure to insuficient cooling, I added a 120 vent with the same results.

digaderfox · Post by **digaderfox** » Thu Sep 25, 2008 2:44 pm

A quick follow up.
VRM could be the issue.

Here is why : I tried to get the card running with the fan plugged. I just put down the fan next to the card onto the S1.
GPU didn't go higher than 43Â° (73Â° with stock) and memory 51Â° (76Â° stock).

It was runing ok, until I decided to put the fan away from the card.

Doing so made the system hang after almost 10 minutes.

My thoughts are the stock fan is blowing air onto some components around that doesn't get cooled enough with the S1.

I'll try some ramsink, or else a fan.

BTW, thanks for the tip.

Mats · Post by **Mats** » Thu Sep 25, 2008 11:05 pm

Do you have to change the BIOS for that?
Isn't this enough? I'm asking because I haven't tried it myself.

alecmg · Post by **alecmg** » Mon Oct 06, 2008 4:56 am

Coming back to the topic of undervolting

After reading rave reviews about 4670 low idle draw, I noticed that it has significanty lower 2d clocks (and probably voltage) than my 3870. But instead of buying a new card, I can now improve idle consumption with software undervolt

I had great experience with Ati Tray Tools. Latest version allows tweaking voltage (from a set of available choises).
So I set 2d speed to 125/250 (from 300/900) and lowest possible 0,974V
I have no power meter, but the settings appear to be working. Temps drop and PSU fan speeds down (indicating lower power draw).
Somebody could measure actual drop in power consumption.

Now my only worry is to replicate this under linux, where I spend most of the [idle] time. Probably have to look into bios mods.

alecmg · Post by **alecmg** » Sun Oct 12, 2008 11:57 pm

Happy to report
Using Radeon Bios Editor and WinFlash, I easily inserted custom speeds and voltages into bios of my Gigabyte 3870.
Now I enjoy lowered power consumption both in idle and load. Don't have a power meter, but hoping that power numbers approach those of those new 4670s

mkk · Post by **mkk** » Mon Oct 13, 2008 5:40 am

I just did the same on my 3870. After having run ATI Tray Tools for a couple of days to verify stability of clocks and voltage levels I put 2D and UVD modes to 300/300 with 1.026V (the lowest I could pick) and 3D to the standard 777/1126 but with one notch lower voltage. For safety I didn't touch the bootup clocks(Clock info 00). Saving just a couple of watts in desktop mode but more when playing accelerated 1080p video, which 300/300 clocks does fine.

This might just be my training for taming a 4850 card.

kike_1974 · Post by **kike_1974** » Tue Nov 18, 2008 5:08 am

I also have my HD3870 undervolted, with these values:

I've been using it for some time, and I knew that it was saving some watts because of the lowered temperatures. But I finally have had some time to measure the results:

Test setup: Asus P5W DH Deluxe, 4x1GB Kingston HyperX, C2D E6600 (undervolted, 2,[email protected]), 1 WD GreenPower 1TB, several USB devices, everything powered by an antec phantom 500W.

Idle, original bios: 118W
Idle, undervolted bios: 108W

Atitool fuzzy cube, original bios: 198W
Atitool fuzzy cube, undervolted bios: 192W

So 10W at the wall difference at idle and 6W at load.

Estimations:

My power supply has an efficiency about 78% at idle loads, and about 82% at load:
http://www.silentpcreview.com/article241-page7.html
But it is a 3 years old power supply, so probably it is a bit lower now, so let's suppose for example 75% for idle and 80% at load.

It means that the estimated DC power savings are 7.5W at idle and about 5W at load. Not much, but it's something.

Those 7.5W power savings at idle put the HD3870 at a similar level as the HD3650, 2W less than the reference HD3850 and only 3W more than the champion HD4670:
http://www.xbitlabs.com/articles/video/ ... html#sect0
http://www.xbitlabs.com/articles/video/ ... html#sect0

The undervolted HD3870 is quite usable for a 24/7 system and capable of some decent gaming.

I have an asus HD3650 in my other computer, I will put this card in mine to see if the results are confirmed. BTW, powerplay works ok in my HD3650 (the one tested in spcr had some problems with it). My HD3650 get its frequency down to 160MHz with the lowest possible vid. I will inform you of the results of this last test.

EDIT: I have tested the HD3650 in the same computer, and I have measured 109W idle power consumption, more or less the same as the undervolted HD3870, as expected, which confirms the results.

PS. Sorry for my English.

flapane · Post by **flapane** » Fri Dec 19, 2008 3:00 am

How much can I underclock our vga?
I have set 100/250 (sapphire 3850) and I wonder if I can go lower without doing any damage.
Furthermore, I put the 2d and 3d voltages 1 step lower, and it seems rock solid atm (0,974 and 1,094v).
Ah, it seems there isn't any way to control fan via bios, even if I uncheck "INCLUDE IN PROFILE" box... it always use the ATT fan tabel profile, why?

In 3d I gathered about 3-4 degrees by lowering vcore, it seems stable atm:

In idle it dropped from 52 to 43.
What about the amount of watts I saved by tweaking 2d and 3d frequencies and voltages?
Why does the vga work even at 1,094v while it needs over 1,2v at stock settings?