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  Topic Review (Newest First)
12-15-2019 09:29 AM
GTANY I used 7 mohms instead of 8 and everything works flawlessly : the GPU frequency remains stable at 2100 Mhz on 3DMark and Superposition now, whereas it strongly decreased before the shunt mod (non-A chip). I did not flash any bios, I used the default one at +112 %.

On air, the card is unusable, the GPU gets too hot, even with the fan at 100 %. On water, it is about 43°C with a universal chinese waterblock. I used 2 fans on VRM and RAM but I added 1 extra fan because the powerstage gets hot (around 85°C). Now, with 3 fans, everything is cool.

Thank you for this thread : I spared hundreds of dollars by buying a simple non-A chip while being as fast as a high-end 2080 TI.
09-13-2019 10:37 AM
chibi I ended up getting a set of 5 mohm for my current Titan Xp, and a set of 3 & 8 mohm if I decide to upgrade soon.

I had purchased a set of 5 mohm in the past, but the parts are so small I forgot where I put them, lol.
09-12-2019 07:15 PM
Asmodian
Quote: Originally Posted by tijgert View Post
I seem to recollect that it was in a thread here, maybe even this thread. Mr.Fox maybe?
That was using another 5 mOhm resistor on top, not 7 mOhm.

I have only seen 2.5 mOhm, 3 mOhm, and 3.08 mOhm resistor values tested by anyone. We have no idea if 2.917 mOhms is too low. I suspect it is not because 2.5 mOhms worked for me with some workloads, like Firestrike Extreme. I think 2.5 mOhms is only barely too low.

Quote: Originally Posted by JackCY View Post
8 mOhm should work, or you can use a 10 mOhm, both raise the power limit a lot and are easy to buy.
Going up to 10 mOhms lowers the increase in the power limit a good amount, 50% more power instead of 62.5% with 8 or 71.4% with 7.
Where I sourced them everything was easy to buy, in ~1 mOhm steps from 1 to 20+ mOhm. 3s, 5s, 6s, 7s, 8s, 10s, 12s, or whatever you wanted for about a dollar each.
09-11-2019 03:45 PM
JackCY The cards have multiple modes and transitions during their operation, so you don't want to be riding the edge and then have it go to weird clocks at certain times or do it sporadically.
The lowest usable value used to be 2.5 mOhm for Paxwell/Maxwel? Now with Turing it's 3 mOhm.

If you want to "remove it" entirely then it's a more complicated thing to do where you could short the power pins or use a very low resistance but report what ever you want onto the sensing pins, meaning you could limit it such that it always stays within the stock power budget values. Too much hassle to bother really and you can't simply lock it to a single value I believe as that also makes it go to a "safe mode" when it's reading high power draw on idle for example. So you need a "smart" system/circuit that does the limiting: min(read_value, my_max), don't know if this can be done somehow simply with a basic circuit.

8 mOhm should work, or you can use a 10 mOhm, both raise the power limit a lot and are easy to buy.
09-11-2019 01:20 PM
tijgert
tijgert

Quote: Originally Posted by chibi View Post
Interesting, where was these results reported?

Good to know I'll take the 7 mohm resistors out of my cart, would you be able to provide the source as well? Thank you
I seem to recollect that it was in a thread here, maybe even this thread. Mr.Fox maybe?
He did all the tests and calcumalations, had nice pics too, and he discovered that lowering the resistance to below 3 mOhm would put the card in safe mode, no matter what he did.

1 / (1/5 + 1/8 ) = 3.07 mOhm, the absolute minimum you can get and still have it work.

He did all the testing for you so you wouldn't have to. But I am not too proud to say I told you so, so go right ahead
09-11-2019 10:49 AM
chibi
Quote: Originally Posted by JackCY View Post
Weren't there reports even with 3.08 or 3.0 already occasionally causing low clocks?

Interesting, where was these results reported?

Quote: Originally Posted by tijgert View Post
I will gladly take that bet. It’s been done, it didn’t work.

Good to know I'll take the 7 mohm resistors out of my cart, would you be able to provide the source as well? Thank you
09-11-2019 05:43 AM
tijgert I will gladly take that bet. It’s been done, it didn’t work.
09-10-2019 07:14 PM
JackCY 7 is s weird value for a resistor. Resistors are made in specific ranges, I think the mOhm are simply rounded to whole numbers.

Even only putting lower current sensing resistors on the power cable inputs alone will give you a gigantic boost in power limit. 5 mOhm vs 3.08 mOhm. Over 60% boost is more than enough and if you need more then you're probably better off soldering on a new power delivery altogether.

Weren't there reports even with 3.08 or 3.0 already occasionally causing low clocks?
09-10-2019 06:16 PM
Asmodian
Quote: Originally Posted by tijgert View Post
Do not use 7, you need 3 total and tacking on 8 will give you just 3. Tacking on 7 will get you a total of below 3 and that triggers safety mode. Do not try it.
Have you ever seen anyone test this? 7 will give you very nearly 3 mOhms, 2.917. I bet using 7 would work... I really wish I tested it first. If/when I change the paste on my GPU I will switch to 7 mOhm shunts just to test it.
09-10-2019 06:13 PM
tijgert Do not use 7, you need 3 total and tacking on 8 will give you just 3. Tacking on 7 will get you a total of below 3 and that triggers safety mode. Do not try it.
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