Underclocked and undervolted 4870

[Comdrpopnfresh]

I edited my bios so that at idle, my core is 250mhz with a 1700mhz(eff) memory clock. It is also undervolted to 1.083V, though it was further reduced to 1.023 by checking "decrease voltages/already decreased" in RBE.

Sometimes I get intermittent flickering on my secondary display, but while selecting a window or maximizing/minimizing I get screen shaking and flickering. No clue why- the gpu usage stays in the single digits.

 

[Qbah]

Originally posted by: Comdrpopnfresh
I edited my bios so that at idle, my core is 250mhz with a 1700mhz(eff) memory clock. It is also undervolted to 1.083V, though it was further reduced to 1.023 by checking "decrease voltages/already decreased" in RBE.

Sometimes I get intermittent flickering on my secondary display, but while selecting a window or maximizing/minimizing I get screen shaking and flickering. No clue why- the gpu usage stays in the single digits.

This link, the third post from the top, is the most extensive read on downclocking/undervolting a HD4870. Read it carefully, a very educational post.

As for the flickering, there's nothing you can do about it. According to the guy from the link, the reason for it is the dynamic clock/voltage adjustment in the BIOS based on the current load - it's a GDDR5 problem. The HD4870x2 uses a different way (drivers perform the change) and it does change the voltage/clocks without the flicker, however it has some other drawbacks - like the card not going into high gear when the application isn't running fullscreen (to name one).

 

[thilanliyan]

No problems with flickering here and I'm using ATI Tray Tools to underclock/undervolt to 550/400 mem. Also update your drivers if you haven't already as the older ones have the flickering issue and I didn't get it with 9.4.

When is it flickering?

 

[Comdrpopnfresh]

when I scroll in webpages, don't have any single window selected (when exiting a program), and when minimizing and maximizing windows

 

[Comdrpopnfresh]

Is it that doing any of those things makes the gpu go from low->high within power state 3; fast enough that monitoring programs don't show it? Also, what is power state 2 for? I did some small clock changes to the bios, enough to let me differentiate between the 10 clock settings, and never hit any of the three in power state 2. For that matter, when does uvd become enacted? It doesn't seem to be used when watching, say, recorded television in media center.
I wish there was a way to control how the gfx card changes between the three levels in a given power state. Then I could maybe find levels for clocks and voltage that wouldn't make transitions in the levels cause flickering: Like how a cpu w/ eist or c'n'q enabled shouldn't jump to the highest p-state w/ a ms jump in usage.

 

[thilanliyan]

Which driver version are you running? I was having the issue with previous drivers (before I started using Tray Tools) but since I've started using 9.4 I have not had that issue.

 

[Comdrpopnfresh]

I am running 9.5. It's confusing trying to settle this issue. Just changing the voltage can make the screen shaking happen- and changing the voltages and clock speeds is far worse. I'm beginning to think maybe the 2nd performance table is used for transitions, and that the amd graphics cards don't run state transitions like cpus, as I'm familiar with.

 

[thilanliyan]

I don't understand why people have this flickering issue. I have a reference 4870 1GB and use ATI Tray Tools to fix the 2D and 3D clocks and have not had this issue since I started using Tray Tools. Also, from what I've read, newer drivers shouldn't exhibit this issue.

 

[Sylvanas]

Flickering is caused by the different frequencies for each memory clock domain. Download GPUtool from techpowerup and you'll note there is a '3D high' 3D'med' and '3D low' settings and the same for 2d. The flickering is caused when, for example you set the memory clocks in the '3D High' domain and not the other 2 domains. So to alleviate this, set the same memory frequency in all 3 domains and it will solve the flickering.

A program like Rivatuner sets all clock domains to the same frequency when you use it's OC tab, while other apps may only set the '3D high' domain which would exhibit flickering.

 

[Comdrpopnfresh]

I don't have any problems with the clock speeds- especially the core speed. I can run 250/1200(eff) with no flickering. But doing so at 1.02 volts and having the med and high clock realms with any higher voltage causes the flickering. The sad thing is that changing the core speed does little for power savings, and reducing heat. However, changing the voltage and memory speed can significantly decrease the temperatures and power draw. I could put up with the flickering, but I actually use both monitors.

 

[Hauk]

Very timely post OP. I have two coming today and plan to work with bios settings.

Thanks for the info friends..

 

[thilanliyan]

Originally posted by: Hauk
Very timely post OP. I have two coming today and plan to work with bios settings.

Thanks for the info friends..

If you can, avoid changing BIOS settings to change OC and fan settings. IIRC flashing the BIOS voids warranties and also someone also recently tried to flash his 4870 1GB to another BIOS and almost bricked his card. It's really easy to use ATI Tray Tools.

 

[Hauk]

Originally posted by: Sylvanas
Flickering is caused by the different frequencies for each memory clock domain. Download GPUtool from techpowerup and you'll note there is a '3D high' 3D'med' and '3D low' settings and the same for 2d. The flickering is caused when, for example you set the memory clocks in the '3D High' domain and not the other 2 domains. So to alleviate this, set the same memory frequency in all 3 domains and it will solve the flickering.

A program like Rivatuner sets all clock domains to the same frequency when you use it's OC tab, while other apps may only set the '3D high' domain which would exhibit flickering.

I just read Qbah's TPU link.. I think you're dead on Sylvanas. The same mem frequency across domains appears to be key.

What stinks is, lower memory clocks appear to provide the greatest power savings, even over voltage reductions. In contrast, only slight heat/power improvements were seen with adjustments to 2D core clocks.

 

[Comdrpopnfresh]

Originally posted by: Hauk
Very timely post OP. I have two coming today and plan to work with bios settings.

Thanks for the info friends..

two what- 4870's? Let me know if you need help or want to know anything...
the closest I came to ruining my card was a false alarm- a stick of ram went bad, and the post led's on the back of the 4870's pcb lit-up an error code + the fan didn't spin up. Like I said- false alarm; pulled the bad stick, it's all good.
oh, and you shouldn't have flickering issues if u only have one monitor

 

[Comdrpopnfresh]

I'm wondering if my screen flickering (which is only on my second monitor btw) is caused by timing or bandwidth differences. I think the fullscreen (19" secondary lcd) operates on a lower dvi frequency compared to the main 23" widescreen. However, I have the alternate dvi and reduced dvi frequency in the ati control panel unenabled- good going, or no?
Listed under "video bandwidth" using a program, the 23" reads 170MHz, the 19" reads 140MHz. Additionally, the two monitors are obviously running at two different resolutions, and so are the refresh rates: the 23" is at 60Hz and the 19" is at 75Hz. Any ideas what exactly 'video bandwidth' is? I'm wondering if I drop the one monitor down to 60Hz as well, if it will make any difference.
Thanks for the heads up about flashing. I use rbe to modify my stock bios; I do not flash another card's bios to mine. And I use atiflash via a bootable usb flash drive to flash... winflash makes my system pause for an uncomfortable length, and I'm afraid of bricking things outside a dos prompt.

 

[evolucion8]

I also experimented the same flickering, but it was an issue when I touched the GDDR5 speeds when I went lower than 400MHz, in the end I had to left the RAM speed untouched, but GDDR5 power consumption is very low when is doing nothing. I think that GPU power consumption is more important. specially when lowering voltages.

 

[Hauk]

Success!

Up and running is 4870 x3 OC'd for 3D and underclocked/volted for 2D. Yea I added a third card. Such a good price, I couldn't pass it up

I'm using these. It's a non-reference cooler that does a decent job, but cards idle in the 60's. At idle, fan runs at 50% which may sound high but it's a 3,200rpm fan. They're quite tolerable to about 70%. Fortunately they're not getting near that mark during 3D.

I modded bios using advice found in TPU thread. Idle temps dropped from 63c to 43c, load in the 60s. I rarely encounter screen flicker, usually see opening GPU-Z, startup/shutdown, and ever so slightly when IE opens. It's worth having 3 cards running in the low 40's.

GPU-Z

GPU-Z

RBE 1

RBE 2

RBE 3

RBE 4