7970 different voltages.

[Dravonic]

After some googling I found out that 7970s are shipping with 3 different voltages, namely 1.05, 1.112, 1.170 with the latter being the most common. According to MSI Afterburner, mine is at 1.05 voltage.

Am I right to think that since 1.170 volts is the most common, I might as well just up the voltage to that, overclock it to my hearts content, considering I never even tweaked the voltage on my card? Would it be safe to go even further?

 

[chimaxi83]

Which specific card do you have? Dependent on cooling, Tahiti can take some voltage, within reason of course.

 

[Dravonic]

It's a reference VisionTek. Not sure if I can get more specific than that.

 

[chimaxi83]

I had none, sadly hadn't return it because of coil whine. I had that one water cooled with a daily overclock of 1200 MHz at 1.25V. If you use a custom fan profile to keep it relatively cool, 1.2V should be fine and run very cool. GHZ edition cards are shipping with a stock voltage of 1.25V so that should tell you something.

Have you tried overclocking at its stock voltage though?

 

[philipma1957]

use msi afterburner to oc. most reference cards will do 1.2 volts with a clock of 1075. no problem. set the memory to 1.55 volts and run it at 1400.


check your temps and your fan speeds.


I can run all my reference cards at 1.2 volts and clock to 1100. I do set memory lower as I run my gear for bit coin. I had 16 gpus now I have 12. all the reference cards could do 1.175-1.2 volts and clock to 1150 but I set ram low 1.5 volts and 800. fans at 65-70 load of 99% 24/7 for bit coin. I don't run that high since they pull too much power but every reference card could do it.

 

[Dravonic]

Stock voltage I can push it to 1025/1575. Not bad but why stop there? So I'm giving overclocking with voltage tweaking a try. But that's a bit nerve-wrecking to be honest, so I want to make sure I'm not doing anything stupid.

It seems quite reasonable to think that my card is in under voltage by default, but maybe it isn't really. I mean, it must have been set low for a reason. I might be straining something other than the core chip along with it, and even though the core chip can take it, that something else can't, and I end up with a busted card.

 

[Elfear]

Stock voltage I can push it to 1025/1575. Not bad but why stop there? So I'm giving overclocking with voltage tweaking a try. But that's a bit nerve-wrecking to be honest, so I want to make sure I'm not doing anything stupid.

It seems quite reasonable to think that my card is in under voltage by default, but maybe it isn't really. I mean, it must have been set low for a reason. I might be straining something other than the core chip along with it, and even though the core chip can take it, that something else can't, and I end up with a busted card.

The reason it was set low is because AMD tests the cards and assigns a default voltage depending on how "leaky" they are. Generally higher leakage parts require less volts to hit the same speeds as low leakage parts. So AMD lowered the voltage on high leakage chips to narrow the TDP variation amongst all 7970 cards. For low leakage chips they raised the voltage to be able to hit the stock clocks.

My first 7970 is a 1.05V card. IIRC, at stock voltage it would do 1125Mhz and at 1.178V it would do 1225Mhz on the stock cooler. You'll probably hit a wall before the cards with higher default voltage because of the VRMS being overworked. I hit a wall at 1225-1250Mhz before switching to watercooling.

I wouldn't worry about raising voltage to 1.175 (or even 1.25V) since some cards come with that at default.