Topic: My findings re power use by GPUs (Read 3181 times)

I did some research re my 6970.  There were 2 problems:  1)  gpu disabled in Catalyst (not connected to monitor)   2)  clock speeds were at 2d speeds (ie much slower than they should have been, a problem others are having with this card, hence forum posts etc).

I did have a dummy dvi plug attached to this card, but it was in the wrong dvi slot.  I changed dvi slot, and suddenly the 6970 was enabled in Catalyst (that was easy!).
Once card was enabled in Catalyst, all I had to do was specify clock speeds, and gpuz confirmed that the card was running at the Catalyst clock speeds.

Now the card is consuming more wattage:  250watts, which is still lower than cards with a stock cooler.

With the Arctic Extreme III cooler installed, I've checked the gpuz temps, and all are very low. Screen shots :

https://drive.google.com/file/d/0B5qUFCCYd3cTN3dlajVmb0c3YmM/edit?usp=sharing

https://drive.google.com/file/d/0B5qUFCCYd3cTdTIyX2wwRGktYlU/edit?usp=sharing

https://drive.google.com/file/d/0B5qUFCCYd3cTTHk5SmZTbDZiWEk/edit?usp=sharing

So, my journey getting this card working properly is nearly finished, just a little tweaking with overdrive to come.

The Arctic Extreme comes with heatsinks for the VRMs etc, I guess that would take care of them?  Certainly upgraded treatment than when the stock cooler was installed.

I've taken some screenshots with some info on the 6970.  You're welcome to comment.


https://drive.google.com/file/d/0B5qUFCCYd3cTaWZXeG9hSjA1VXc/edit?usp=sharing

https://drive.google.com/file/d/0B5qUFCCYd3cTV0c2Y21RUzlCTFE/edit?usp=sharing

https://drive.google.com/file/d/0B5qUFCCYd3cTVHpGNi1CSDhOQXM/edit?usp=sharing
(I don't know what relevance the 6970 being disabled in CCC is, it still seems to work...)

Yo can be fine with that psu, but 40W for 6970 is absolute bullshit. IT eats a lot of power, i had one once. No metter what cooler you use. Also be carefull with aftermarkets. Although they cools gpu itself very well, vrms will go very high on temps. That is critical for your stability. Also you may be using low intensity with that 6970, give us a screenshot where it shows how much it can mine and temps too.

I currently have 1 x 6970 & 1 x 7970 in my mining rig.  I'm mining terracoin & litecoin, not bitcoin.

I want to add a 2nd 7970 gpu for helping me mine litecoin.  I was looking at the power requirements for adding this 3rd gpu, since my psu is an Antec Quattro 1000w, and all existing 12v rails have been used.  I was thinking of splitting the 12v rails for each rail to feed both pcie connections (although I've read that this is supposed to be a bad idea).

OK, so I found out what my existing 12v rails are rated at 18amp each.  I began to realise that whatever I did to power my gpus, it all depended on  1)  what power usage my gpus require   2)  how many amps the 12v rails can handle.

The amperage specs on my psu are here:
http://www.overclock3d.net/reviews/power_supply/antec_truepower_quattro_1000w_atx_psu/1

However it occurred to me that I needed to know how many watts my gpus were using.  Several internet listings of various gpu watt usage differed, so I decided to put a watt meter on my PCs power cable, and check the watt usage etc.

What I found really interested me.   My 6970 gpu has Arctic's Extreme III cooler on it.  My 7970 still has its stock cooler (single fan on back of case (which apparently means its a reference design?)).    I mine terracoin with my 6970, Litecoin with the 7970.   I first noted the watts used without any gpu mining (peaking about 120 watts).   Then I mined using each of the gpus in turn.  6970 really surprised me.  When mining using cgminer, the watts only increased by 20 watts!!??   When I mined using the 7970 only, watts increased by approx 260 watts (less than I expected).   I decided to test the 6970 further, and loaded the PC after uninstalling the 6970 (riser disconnected, pcie power cables disconnected).   The PC usage watts (without any mining) was about 100 watts, meaning that the 6970 was potentially only using only 40 watts!!  (still surprising).   

This exercise taught me that the fans on these gpus really eat a lot of juice!  The stock fans seem to eat far more juice than the aftermarket fans (certainly the one I'm using!).   I need to change the fan on the other gpu (and on any new gpu).   This also taught me that IF the gpus are using so little juice, I CAN probably split the 12v rails and easily stay within the amp rating of the rails (which is cool).   

If upgrading the coolers reduce the watt usage so much, I guess one would be able to have much better usage/mileage out of the PSUs!