Which 7950s and 7970s can be undervolted?

[Vesku]

Is there some list maintained somewhere on the internet? Specifically I'd like to find out how ASUS, MSI and Gigabyte model 7950s and 7970s handle undervolting.

 

[RussianSensation]

Way too hard to answer with good accuracy:

1) Depends on ASIC lottery;

2) Some already ship undervolted, leaving no room to undervolt, others ship at stock voltage leaving room to undervolt but that only matches other cards that already ship undervolted from the factory (Sapphire Dual-X 7970 OC, MSI TF3 7950).

3) Undervolt to what speed?
- HD7950s are clocked from 800-950mhz.
- HD7970s are clocked from 925-1100mhz

4) You can get a 7970 and undervolt it way lower to match an after-market 7950's performance but it won't be a 7970. Or you can buy an 7950 that overclocks to surprass a 925mhz 7970 but uses less power.

I am guessing you want to undervolt to reduce power consumption? That makes it even less tricky since some cards have premium components which are far more efficient for power delivering, dropping power consumption significantly. For example, the Gigabyte SuperClock consumes 29-35W less power than a reference 7970 GE.

IMO, your best bet would be to get cards that are known to be good overclockers since they are more likely to handle undervolting - so that's MSI TwinFrozr 3 7950 or PowerColor PCS+ 7950 or Sapphire Dual-X 950mhz HD7950, Sapphire Dual-X 7970 OC (but that's now replaced by the Vapor-X and no one reviewed it yet), MSI Lighting 7970, Gigabyte Windforce 3x. Again, you'll be playing the ASIC lottery here. MSI TF3 7950 seems to get very good chips based on feedback and its overclocking.

Also, how does one even guess at what voltage say a Gigabyte GE7970 1100mhz would need at 925mhz? Would that card use less power than a stock 7970?

 

[Vesku]

Thanks for the info, I remember reading something about at least one ASUS card locking out undervolting. Was that a true statement or just a misconception?

My current interest is in a model of 7950 that will use the least power among the listed brands at ~1GHz.

Here are a couple I'm looking at on Newegg:

MSI R7950 Twin Frozr
http://www.newegg.com/Product/Product.aspx?Item=N82E16814127667

Gigabyte 7950 WindForce3
http://www.newegg.com/Product/Product.aspx?Item=N82E16814125414

 

[Arkadrel]

@Vesku

Ive read about the Asus DCII as well, haveing "locked" voltage settings.
Apparnelty this "hardware locked" voltage is a Asus thingy.

because: (from: http://hardforum.com/showthread.php?t=1694176)

The 680 Direct CU II is hardware voltage locked.

Confirmed that the 7970 Direct CU II is voltage locked - possibly at 1.188 V.

Just avoid buying those (Asus models)
Or stick with reference designs.


Usually this "hardware locked" voltage is because their too cheap to use a decent chip for voltage regulation, or atleast thats how it is with the low end graphics cards that suffer from this.



***edit:
http://www.techpowerup.com/forums/showpost.php?p=2661155&postcount=9

^ someone found out how to custom edit a bios for the Asus DCII 7970, and get it to unlock the locked voltage settings.
(my opinion is Asus suck for locking things, the more controll the user has the better, always)

 

[RussianSensation]

MSI R7950 Twin Frozr
http://www.newegg.com/Product/Produc...82E16814127667

Do you have to buy at Newegg only? The TF3 is $20 cheaper at Superbiiz. Also, if you strongly care about power consumption, GTX660Ti may be worth waiting for.

 

[Vesku]

No, I do not have to buy from Newegg. Just used it for linking what I was considering. If I settle on it I will be considering several sources including Superbiiz. Also, I want to bitcoin mine when not gaming so Nvidia's 600 series is out unfortunately.