Easy undervolting guide for 79xx and R9 280X cards

[Dego]

something is really ****ing with my bioses

I have removed that card#1 that has 1.2V default and inserted the card#3 thats not been flashed with the card#2 that performs best and has default voltage 1.16. And its pushing #3 card also to the limit and also 1.2V default.
After that i've removed #2 for #1 and bios is not the same anymore and when I try to load it it says "Invalid checksum!" but then it shows VDCC 1200 but I've set it to 1144 previously.

So something is ****ing me really nice. I can't complain about the performance of the cards because I get 760KH/s.

So what are the possibilities here now?

I've gotten 1 great card that has low stock Voltage and others are not?

I will try removing drivers tommorow. But the rig is freshly installed win 8.1 from today. I will probobly have more answers in two days when I get my PSU adapter so I will hook up 4 GPU's.

 

[ZL1]

for testing purposes try messing with a single card at a time
the install may be fresh, but i mean drivers can get stuck to the old bios so to speak, again ive not seen this exact thing happen before, but ive seen drivers get in the way of a bios flash before in a different way

 

[KonaKona]

Just used this to overvolt my 240!

 

[Silver_Pharaoh]

I'm lost now. Are you upset that the card is undervolted and nothing is showing the correct voltage??

 

[Dego]

I forgot to mention, when i try to load the stock BIOS with VBE7 I get this message "UEFI image detected! Modifications only affect the legacy BIOS, UEFI part will be disabled!"

 

[KonaKona]

I forgot to mention, when i try to load the stock BIOS with VBE7 I get this message "UEFI image detected! Modifications only affect the legacy BIOS, UEFI part will be disabled!"

I got this when trying to mod the bios on my 7850. Couldn't get anything to stick. Donno what it means exactly but it seems to translate into "you can't flash me".

 

[Dego]

So now i've tryed to undervolt on of my 280x in my main computer and it works. Looks like the drivers or something overrides the bios and it stays on stock voltage.

Can I use 1 bios for all 4 GPU's?
And if I want to go lower voltage than 1144 I have to set #6 and #0 to same number right? for ex. 1094.

 

[KonaKona]

So now i've tryed to undervolt on of my 280x in my main computer and it works. Looks like the drivers or something overrides the bios and it stays on stock voltage.

Can I use 1 bios for all 4 GPU's?
And if I want to go lower voltage than 1144 I have to set #6 and #0 to same number right? for ex. 1094.

What drivers are each rig using?

 

[ivanlabrie]

Exactly, experiment and see if lower is stable.

 

[Dego]

Drivers: 13.12

So now i've flashed #1 GPU in my personal computer to vdcc 1.075 but when I insert it to my rig it is flashed but vdcc is 1.090 confirmed by cgminer and GPU-z. So at least i'm making progress. Going to start flashing other cards 1 by one in my main computer.

Can I use bios from my #1 GPU on other 3?

EDIT1: I have removed 13.12 and installed 13.9 and now cgminer and cpu-z show the correct vdcc of 1.075

 

[KonaKona]

You might be able to if they are the exact same make and model but it's safer to do the backup/flash process for every card, in case one of them has different ram chips or whatever. I think that makes a difference?

 

[Dego]

After 20min of mining these are my results

GPU0: vcore 1.075v
GPU1: vcore 1.131v

All are runing 1100Mhz/1500Mhz

Should I be happy with these results?

These are the minimum, if I go lower I get driver crash. Also I've flashed #3 GPU it's also 1.131V can't go lower. Going for the #4 now.

And I still cant undervolt on my rig I have to do it on my main computer. I really don't care that much but still I don't like the idea that I can't do it. I have an ASrock H61 mobo. Should I upgrade my firmware? I haven't done it when i've installed win8.

 

[Silver_Pharaoh]

After 20min of mining these are my results

GPU0: vcore 1.075v
GPU1: vcore 1.131v

All are runing 1100Mhz/1500Mhz

Should I be happy with these results?

These are the minimum, if I go lower I get driver crash. Also I've flashed #3 GPU it's also 1.131V can't go lower. Going for the #4 now.

And I still cant undervolt on my rig I have to do it on my main computer. I really don't care that much but still I don't like the idea that I can't do it. I have an ASrock H61 mobo. Should I upgrade my firmware? I haven't done it when i've installed win8.

Looks good.
What cards were they? 280x's?

 

[Dego]

Gigabyte 280x rev 2.0

My #4 gpu is minimum 1.094V. Going to lower my CPU speed so I can get lower temp. and lower fan speed.

That's it for today see you tommorow when I connect all 4 GPU's and with my luck some new problem will present itself

 

[KonaKona]

Gigabyte 280x rev 2.0

My #4 gpu is minimum 1.094V. Going to lower my CPU speed so I can get lower temp. and lower fan speed.

That's it for today see you tommorow when I connect all 4 GPU's and with my luck some new problem will present itself

Speedstep or whatever it's called nowadays should be enough for this. You shouldn't have enough CPU load to run it much past min clocks.

 

[Dego]

sorry don't understand?

 

[ivanlabrie]

He means that the cpu will run undervolted/clocked if you don't touch anything and don't mine on it.

 

[KonaKona]

He means that the cpu will run undervolted/clocked if you don't touch anything and don't mine on it.

Specifically, CPU mining. If you are GPU mining, your CPU should be unused, and the CPU will automagically underclock and undervolt itself when it's not being used. You can use CPUz to check this for yourself. My 2500k runs at 1.6ghz or so and I think .8vcore, instead of 3.4ghz and 1.2vcore... I think.

But yeah, you shouldn't have to do anything to your CPU.

 

[xsuperbgx]

I have an amd dual core that runs almost maxed out with 4 cards mining. So there is some CPU load sometimes.

 

[KonaKona]

I have an amd dual core that runs almost maxed out with 4 cards mining. So there is some CPU load sometimes.

What coin/alg are you running?