2x7950 + 6570 =cant change voltage in Afterburner

[Shumiha]

Hello!
I used 2x7950 and Afterburner let me control voltage without problem. But after I plugged in another 6450, then replaced it with 6570 and connected my monitor to it, Afterburner wouldn't let me change voltage, (any changes in the configuration of AB does not change anything) I can only change core and mem frequency of these 3 cards, but no voltage. If I remove 6570 and connect monitor to 7950 the voltage can be modified again. I tried installing Asus Tweak, but it sees only 6570. As 7xxx's BIOS can be modified I'm looking for a way to change voltage. I'll be happy if you help me find a solution how to be able to change voltage on 7950 while keeping my monitor connected to 6570. Thanks in advance!

P.S.
I tried AB 2.2.0, the latest and some another version
Catalyst 12.6 and 12.8
I'm using win7 x64

p.s.s no affect with riva tuner and att

It's what I spotted in the AB window about video hardware information--

GPU1
________________________________________________________________________________
Display device : AMD Radeon HD 6570
Display driver : Catalyst 12.8
BIOS : 013.012.000.041
GUID : VEN_1002&DEV_6759&SUBSYS_E193174B&REV_00&BUS_1&DEV_0&FN_0

GPU2
________________________________________________________________________________
Display device : AMD Radeon HD 7900 Series
Display driver : Catalyst 12.8
BIOS : 015.013.000.010
GUID : VEN_1002&DEV_679A&SUBSYS_04241043&REV_00&BUS_4&DEV_0&FN_0
Multi-GPU role : master

GPU3
________________________________________________________________________________
Display device : AMD Radeon HD 7900 Series
Display driver : Catalyst 12.8
BIOS : 015.013.000.010
GUID : VEN_1002&DEV_679A&SUBSYS_04281043&REV_00&BUS_5&DEV_0&FN_0
Multi-GPU role : synchronized with master

 

[BarbaricSoul]

Why are you trying to run a 6570 with a pair of 7950 cards?

 

[Shumiha]

Why are you trying to run a 6570 with a pair of 7950 cards?

mining

 

[RCoon]

Trixx should let you change the voltage on all of them. Install and disable ULPS or whatever it's called. Also i presume you're trying to lower the voltage if you're mining?

 

[Shumiha]

Trixx should let you change the voltage on all of them. Install and disable ULPS or whatever it's called. Also i presume you're trying to lower the voltage if you're mining?

already install trixx and i see VDDC

but inresting why AB not want give me voltage control 7950

"Also i presume you're trying to lower the voltage if you're mining?" what you mean ?

 

[brandonwh64]

already install trixx and i see VDDC

but inresting why AB not want give me voltage control 7950

"Also i presume you're trying to lower the voltage if you're mining?" what you mean ?

To save power

 

[Shumiha]

To save power

yes,too hot,too much money.

 

[RCoon]

already install trixx and i see VDDC

but inresting why AB not want give me voltage control 7950

"Also i presume you're trying to lower the voltage if you're mining?" what you mean ?

I run afterburner to monitor temps, as it does not allow me to voltage control my 7950's, but i have a rainmeter plugin that uses AB. Then i use Trixx to overclock and take boot priority over AB. No idea what the deal is.

 

[Shumiha]

I run afterburner to monitor temps, as it does not allow me to voltage control my 7950's, but i have a rainmeter plugin that uses AB. Then i use Trixx to overclock and take boot priority over AB. No idea what the deal is.

my english is not godd,but i hope you understand me

i open AB,then Trixx and ab is main because i can change for example gpu clock in Trixx but nothing happen,and i not see change. now i open only trixx.

You take(swith on) rainmeter plugin that uses AB ( ab is open? ab is in "task manager Windows"? ),and then open Trixx and trixx have main priority(all clock and voltage changes become effective) ?