Nice Job on the card mod, and thanks for posting this here to as well. This way it reaches out to far more people in case they happen to have missed out on the 3090 owners club. I'm currently waiting upon a 3090 Strix, and was hoping to get a vbios mod of some sort down the road, I guess time will tell once that becomes available on the forums. However thanks again and good luck

 

Any idea how much power you were drawing from the card before and after? Just genuinely curious how much more power the 12 pin us pulling.

 

Around 350 to 360W before the mod, around 370 - 440W (OC dependent) after if my kill-a-watt is right. I have a dedicated PSU for my GPUs. With a stronger OC on water and pushing the power limit higher I may be able to get a bit more, but I am now hitting the voltage limit of the GPU itself but I've kept the OC relatively tame for the time being as even with chilled air a moderate OC can quickly overcome the cooling solution. So with this shunt mod, I've removed the power limit but I'm now stuck at the GPUs volt limit.

 

You sir are awesome. I have this card and have been wondering what to do. Now my only delimmea is to wait and get a StriX or a Kingpin, or just go all out with the FE. I also have a waterblock on the way the bykski.

 

Awesome thanks!
Would you be willing to run furmark to see what the max wattage used by the card after the mid would be? Trying to find what may be the weetspot for the resistors to try and pull 500-550 watts as I may go this route.

Thanks for adventuring into the unknown for us!

 

I will absolutely do this once I have my water block. Right now on air I can't get things significantly stable enough for a true test of the max power draw. Though from my really horrible math the theoretical max draw should be somewhere close to 600W (in reality it'd probably be around 550 to 580W)
I can guarantee though that using 3mOhm resistors you can easily set your power target and have it draw 500 to 550W based on the math.
You'd just need to play with the power limit in Afterburner post mod until you found that sweet spot using a kill-a-watt or something.

 

Thanks! I'll be looking at doing this once my block arrives.

When running the stock fan curve I'm getting a max fan speed of about 2000rpm at 400W during a Port Royal stress test. My GPU temp is actually lower at max power limit than stock. Probably due to memory temp. Is this behavior the same for your FE's? I am beginning to wonder if the thermal pads aren't installed properly on my card.

 

Nah mine was doing the same thing, as soon as I shunt modded it that changed immediately and the card began going from stable temps on air around 68 to 70 C to around 85 to 90 C when maxing the power limit. They definitely put some heavy restrictions on power draw this gen, hence all the resistors, and I agree that it's probably something to do with the memory heat. I'm currently trying to think up a solution to water cool the memory on the back side of the card better than the bykski backplate. I'm kinda worried about the longevity of the memory on the back of the card when overclocking it now

 

can you share what heatgun you used?

i'm scared of using one because of the components in rnage of the shunts and would probably just stack 5ohm on them

maybe this one would work with the small nozzle? https://www.amazon.com/gp/product/B078S5QMFG/ref=ox_sc_act_title_1?smid=A2S44JINAWVPD1&psc=1

 

can you share what heatgun you used?

i'm scared of using one because of the components in rnage of the shunts and would probably just stack 5ohm on them

maybe this one would work with the small nozzle? SEEKONE Heat Gun 1800W Heavy Duty Hot Air Gun Kit Variable Temperature Control with 2-Temp Settings 4 Nozzles 122℉~1202℉（50℃- 650℃）with Overload Protection for Crafts, Shrinking PVC, Stripping Paint - - Amazon.com

I used a similar one to that, but Black and Decker that I purchased at Lowes. That one would work fine. It's ok to heat up the surrounding components as long as you do not disturb them!!!!!!!!!!!!!!!!!
It takes an extremely steady hand. Just heat them up until the solder melts and using very pointy fine tweezers, lift (do not slide) the old resistors off the pads. Then throw down some solder paste, place the new resistor down, turn the heatgun on LOW mode (high heat but low speed) and melt the solder paste affixing the new resistor in place. If your nervous about it I wouldn't do it, as being nervous can cause shaky hands. I had to have someone else pull the last 2 resistors for me because my hands were shaking so damn bad lol

 

What size fujipoly are needed? Any recommended thermal compound these days, liquid metal? Ordered resistors for shunt mod. I can't break 13500 on Port Royal due to power limit throttling right now. =/

 

I'm not certain on thermal pad sizes yet, still waiting on my water block which won't arrive for another week yet. For thermal compound I highly recommend something like Thermal Grizzly Kryonaut or Arctic Silver. Just use a high quality paste and you'll be fine. I wasn't able to get past 13700 on Port Royal either due to the power constraints, and now that I'm shunt modded on air I can't get past 13900 due to heat constraints I haven't yet tried running Port Royal with the air conditioner hooked up to the PC, but even with that I doubt I'd make it past 14000 as this card gets f'ing hot. Definitely need to water cool after shunt modding or use LN2, no exceptions. I used to have a shunt modded Gigabyte Windforce GTX 1080 that was shunt modded back in the day which actually did just fine on air, but the 3000 series just get ridiculously hot.

 

So lets say we stack 5mohm resistors to bring the power limit up to around 750. Could we set the power limit in afterburner to 67% yo enforce a limit max of 500w?

 

Yeah. When you shunt mod you are simply tricking the card into thinking it's drawing less power than it actually is. So for example say your new power limit is 700W and you set the limit to 50% in Afterburner, your card should only draw around 350W in theory. I haven't really tested this yet, and I'm curious to see how well lowering the limit it software would work as the card isn't really sure how much power it's drawing at this point, so it might not limit it at all. Something I want to check out.

 

8Mohms should only be used when stacking above the 5Mohms. Replacing with 8Mohms constrains power limit. It is quite obvious.

 

Thanks for your post. I am also thinking about shuntmodding my 3080 refpcb. But I will go to stack them on the orignal 5mOhm - soldering would be done from an expert. How dir you choose and dimention your proposal and which type you would choose for 5mOhm size?

Here the pcb:

 

My resistors arrived last night. Went through Tech Jesus' video on disassembly and he mentioned an issue with the backplate causing thermal problems after reinstalling. I then saw that echoed on reddit.

Any actual truth to this? What caused the thermal problems?

 

I have yet to run into thermal issues after removing the backplate. I removed it VERY carefully as to not tear their cloth-like thermal pads.

What source did you find your 3090 FE block?! The place I ordered from sent the wrong one, they sent me the reference cooler, and Aliexpress has a huge effing delay on orders for the FE block

 

@olrdtg Don't like bitspower stuff? i ordered 2 blocks directly from them. They aren't in the US shops yet.

 

Do they have a 3090 Founders Edition block? I thought Bykski was the only manufacturer with an FE block currently

Edit: Nevermind! I found them and they look really nice. I just placed an order for one. Thanks for the tip!

 

Have you measured the power you are drawing from the pcie after shunting it's resistor? Curious as to how much power that 3 ohm resistor is letting it pull. That's the only resistor I'm hesitant on replacing without doing a full reroute of the power to the 12 pin.

 

Still waiting on a water block to arrive before I actually allow it to draw max power for measurement.

 

Alright... shunt resistors, thermal pads and IC graphite pads on the way. Think I'll take it slow, do the two shunts by the 12 pin power connector first and see what effect it has. Then move on to the others. Don't plan to do the PCIe slot shunt and might not do the memory power shunt either, but, I am not sure what effect this will have because of the supposed power balancing.

 

I was only able to achieve success with the shunt by modding all the shunt resistors. All 6 on the FE card. I tried to avoid the PCIe resistor, but not shunting caused the mod to not work. Modding this resistor with 3mOhm should be fine, especially if your motherboard has an auxiliary power input for the PCIe slots (like an extra molex/sata or PCIe 6-pin) connector on the motherboard near the PCIe slots. Most SLI certified boards have them. I've got mine plugged in and I've been stressing the hell out of the card. My 24-pin cables have not been getting warm or anything so all seems fine.

 

Has anyone done full check on exactly which shuts are truly needed? seeing reports of people not even doing the PCI-E slot shut.

 

For the FE, not that I am aware of. Closest I've seen is der8auers video on shunting the 3090 tuf. I am probably going to try doing the two shunts next to the 12 pin one at time to see what effect it has...Just to satisfy my own curiosity. Olrdtg says this won't work.

 

it works, it gives maybe 20-40w extra at least i got better result i used liquid metal on mine 3090 FE.

 

So you added the shunts to the PCIE power as well? I thought we were already pushing the limits of the PCIE slot...?

 

PCIE slot has a 75W power draw limit anyway, so it seems to me that there's no harm in shunting this mod.

 

Ahhh ok, it was just a concern and you did a very good job at addressing my question. I also have an auxillary 6 pin for PCIE power, my only thoughts now, to Shunt mod my FE and keep it because I already have a waterblock on the way, or, dont shunt mod and grab the 3090 strix version, and shunt mod, that... Decisions decisions, +1 on your rep again sir.

 

Put 15m Ohm on all of them is the easiest way to go.
Thats around 100W from slot (should handle it since there were RX580 that were hitting 103W from the slot not that long ago and only boards that blew were super budget boards.)

EVGA,Gigabyte,MSI use fuses on there plugs and slot input.
FE doesnt.

 

Do you expect that same procedure will work on ref.PCB of 3080? So additonal 15mOhm on all 5 resistors on front and 1 on the backside for PCIe?

 

You can work out what your card would get with those using this tool.

GitHub - bmgjet/ShutMod-Calculator: Work out what shunt values to use easily.

Work out what shunt values to use easily. Contribute to bmgjet/ShutMod-Calculator development by creating an account on GitHub.

github.com

 

Thanks but I know that tool. I just want to know if the mentioned shunt positions are the right ones and all needed?

 

Thats all 6 so yes.

 

Yes idea would be to stack them. Should calculate that later in the tool....

 

I'll have to find the post in the 3090 owners club, but running voltage of 1.1-1.15 was able to overwhelm a dual compressor phase change unit. Poster said the chip goes thermo nuclear with heat at that voltage level (was using mm to measure voltage and Elmore for voltage control) so I'm not sure how beneficial voltage modding is unless going ln2.

Though, a large water loop/chilled water setup would probably handel the heat better/longer than a phase change as it should take longer to heatsoak all of the water and rads. The water loop also benefits from recovering from heatsoak much easier and faster than a phase change.

But the the question becomes how well these chips handle higher voltages at ambiant and sub ambiant (0-10*C for chiller let's say) temperatures.

The idea of doing different mohm resistors for the pcie and 8pin/sensors, as mentioned earlier in this thread, is what I was also considering doing. Keeping the pcie under 110-120w while at least getting some extra benefit from the pins with lower resistance shunts. Using a 15 or 20 mohm on the pcie and then trying 3's on the others would be interesting just to see how much total power it is actually willing to pull in total.

Wish we had a better understanding of the algo of the power balancing taking place. Whether it's just some tied ratio between pcie and pins or what.

 

Wish we had a better understanding of the algo of the power balancing taking place. Whether it's just some tied ratio between pcie and pins or what.

The hardware side is known from board tear downs.

2 plug 20/40/40%
3 plug 16/28/28/28%

Controlled by a IC thats doing PWM to each of the input phase control circuits to try balance them to that ratio.
If one input is higher then it trys to reduce that input and boost the others. Software wise it looks to have about a 1-2% tollerance.
Beyond that it just triggers a power limit.

More needs to be known about this controller tho. Like can we interface with it some how to change the power split.

 

I followed the OP's instruction to the tee for my 3080 shunt mod. Many thanks, I would have never attempted this feat if OP didn't provide such detailed instructions and a success story, along with the link to purchasing the right kind of a resistor. The ones linked in the post have big metal blocks and are great for stacking!

The short summary is: it worked - I now have a working shunt mod with power basically unlimited. Here are the few issues I ran into for those beginners like myself soldering for the first time:

1. I used a heat gun and a soldering paste. Thanks to the OP for suggesting this, it was way more precise than soldering AFAICT.
2. I wasn't able to remove the original 5 mohm resistors from the board. I had been practicing on an old scrap board and I had no trouble removing its resistors, but with the actual 3080 board those things looked completely stuck no matter how much heat I gave them. I stopped at 430C on the heat gun as I was too scared to go any higher.
3. I ended up stacking the 3 mohm resistors OP suggested on top of the existing 5 mohm resistors. This basically means unlimited power to the board, but I'm using Afterburner to control the power draw.
4. Even with the soldering paste, this was a nerve-wrecking 2 hours. The biggest fear was that I would connect solder to some other components. I'm not 100% sure if that's a real concern, but honestly some resistors had fraction of a mm clearance to these tiny resistors on the board: I'm amazed folks have the skill to use the soldering gun for their shunting mods. I ended up blowing my heat gun in the sort of right directions, praying that the few balls of solder don't end up flying somewhere else on the board. Ugh.

In any case, it can be done and I'm very glad I did it, but there must be an easier way. Few tips on the temperature on the gun and how long it took to unstuck those resistors would have been great. I feel it would have been way easier to replace than to stack the resistors.

 

I'm glad everything went well for you but PLEASE tell me you didn't stack a 3mOhm on a 5mOhm on the PCIe slot resistor! D: You're going to be pulling around 190W from your PCIe slot. You need to remove that resistor and replace it, or stack a higher value on that one like 8mOhm or 12mOhm instead of 3mOhm. Take that card out ASAP and fix it before damage happens. Pulling 100/120W from the slot is already iffy, but 190W will definitely cause something to melt or burn out in short order.

I can walk you through resistor removal. You need to be very patient on this, and again have a steady hand. Its ok to heat up the components surrounding the resistor, so turn the heat gun up a bit and just hold it over that resistor, occasionally poking at it very gently. Once it's lose, use the tweezers to carefully lift it off. Then use the paste again and slap down a 3mOhm to replace. You only need to worry about the PCIe slot resistor (resistor closest to the pcie slot on the back of the card, I have it marked in the pics with a yellow line)