R9 290 Undervolting

I got a new toy today(ASUS R9 290 DC2OC) and have been playing with for few hours now.
Having satisfied my need to test the cards capabilities I am now facing a problem quite opposite from testing performance.

I noticed that GPU tweak has option to adjust the voltage of this card and having no need yet for that much horsepower so I want to undervolt and underclock this card to allow my case fans run as slow as possible.

The problem is that when I drop my GPU and memclock and then voltage, at around 1.2V I start to get black screen issues. Screen goes black and doesn't recover until hard reset.

My understanding is that reference cards run under 1.2V 950MHz GPU clock so it makes no sense to me.

GPU-Z reports cards voltage at 1.1V but there is no change in that if I drop the voltage from GPU tweak.

This new way of voltage and clock control is completely new to me and I hate it

Voltage will vary on each and every card. Some default at 1.2v others 1.1 or so.

GPUz isn't reading it right if it is not changing. I would imagine that GPU Tweak would show the actual voltage...

new way?

my 290 alos black screens when undervolted

Seems that these chips have very low tolerances. For the rated speeds the voltage isn't exactly forgiving like many older cards had. I'm still kind of baffled about the asus card having quite a bit higher voltage than reference card since it cannot run ref speeds with ref voltages. Putting "bad" chips on custom oc'd cards? seems like probable explanation since the added cooling allows for higher voltage. Or maybe I just don't know any better

I think alot of the issues like this and overclocking too all stem back to the power saving stuff they implemented on this card. the 7970's had basically non of these issues like the 290s do and they are similar architecturally

There is no single stock voltage for these cards. Just like there wasn't for the 7900 series cards. That have a voltage scale based on asic quality. You cannot say one 290x has x.xx volts so stock voltage is x.xx. I have two reference 290s that have different stock voltages.

If you turn down the voltage your Asus came with you are trying to run it undervolted. You are not trying to run it at stock voltage. It came from the factory at stock voltage for its asic score.

I don't know how these cards run on air, but on water they behave almost identically to my 7950s.

Are GPU-Z reported voltages accurate by any means?
My understanding was that these Asus cards came with fixed voltage but apparently that is not the case.
Does AMD release same kind of tech documentation about their GPU's as they do for their CPU's?

Thanks for bringing up the ASIC quality. That helped a ton understanding these cards better.
I come from HD4000 series so it's been a while
My card had ASIC value of ~71% which is average from from what I understand and should be half decent for water cooling.

sorry to ping an old thread. though i've also been experimenting with undervolding and clocking an R9 290x changing volts appear to directly lower the clock as well and vise versa. as in, it'll not boost as high. i have put these settings in afterburner http://puu.sh/bzRt7/8ab555e2cb.png and the voltage does not go above 0.930 regardless of load. these cards are also fast enough to do most games perfectly fine at this clock. for highly intensive games ive saved another profile which is a slightly undervolted stock clock of 1030mhz. http://puu.sh/bzSE5/233a8f8ffe.png