So i am another lucky one who got in the 3090 pad club. Lol. Anyways after reading a bunch on this subject I decided to change pads. after trying a few different pads and getting worse temps I did this. I got the gelid extreme 2.5 pads, the putty that is recommended and used the putty on the memory pads first. Just a thin layer over all memory pads and then uses those 2.5mm gelid pads. I also used notura cpu paste on the gpu itself along with replacing the putty for pads in the vrm. But i also did a light cover of putty on them too. Used a 1mm over those and used a 2.0m and a 1.0m on the other thin pad. Got my temps in a decent warm room to 90c and i found if i put a cpu cooler with fan in the back side of card i can drop the temps another 8c to 12c. Amazing. Ive ordered a big heatsink for the back and have fans for that. Just wanted to share my journey with it. Oh my old readings were 96c in a room with the window open and a fan on it.

gmzombie
So i am another lucky one who got in the 3090 pad club. Lol. Anyways after reading a bunch on this subject I decided to change pads. after trying a few different pads and getting worse temps I did this. I got the gelid extreme 2.5 pads, the putty that is recommended and used the putty on the memory pads first. Just a thin layer over all memory pads and then uses those 2.5mm gelid pads. I also used notura cpu paste on the gpu itself along with replacing the putty for pads in the vrm. But i also did a light cover of putty on them too. Used a 1mm over those and used a 2.0m and a 1.0m on the other thin pad. Got my temps in a decent warm room to 90c and i found if i put a cpu cooler with fan in the back side of card i can drop the temps another 8c to 12c. Amazing. Ive ordered a big heatsink for the back and have fans for that. Just wanted to share my journey with it. Oh my old readings were 96c in a room with the window open and a fan on it.

WHAT BACKPLATE /HEATSINK W/FANS DID YOU BUY? I'VE BEEN LOOKING BUT CAN'T FIND ANYTHING OF REAL QUALITY OUT THERE I'D SPEND MY MONEY ON, I'D LOVE TO ADD THAT TO MY CARD. I JUST SPENT $225 ON THERMAL PADS AND PASTE.

There is a website that sells precut thermals pads. Though I have no experience or affiliation with them yet (If I need pads, I will go through them.) I have only heard positive things about their pads, though these positive things did come from internet strangers.
Their kits include the right sizes and thicknesses for if I remember correctly for most EVGA cards and sku's. Sorry if this sounds like an advertisement, but it seems like it would take a lot of the guess work out and be more convenient. 
 
https://kriticalpads.com/Custom-GPU-sets_c_11.html

Yea i just looked up a 3090 backplate heatsink on Amazon and it popped up. Im gonna use what i have from and old cpu heatsink for the fan.

Just ordered a set and I'll report back once they arrive and I get them installed. Thanks! 

I've got the best temps outside of double-blocked cards I know of.  My adventures on what works is documented here https://imgur.com/a/OXoYmeb
Card's 24/7 setup is 126+mhs at 280w, 70c.

Kingofroam
There is a website that sells precut thermals pads. Though I have no experience or affiliation with them yet (If I need pads, I will go through them.) I have only heard positive things about their pads, though these positive things did come from internet strangers.
Their kits include the right sizes and thicknesses for if I remember correctly for most EVGA cards and sku's. Sorry if this sounds like an advertisement, but it seems like it would take a lot of the guess work out and be more convenient. 
 

Anyone try this? I'm looking to cool my card and it seems promising

https://www.overclock.net/threads/3080-3080ti-3090-series-replacement-thermal-pad-sets-20m-wk-online-order.1795421/

https://www.overclock.net...-ultra-gaming.1795976/

I'm a fan of these myself https://www.reddit.com/r/...0ti_copper_mod_ver_20/

//// Update: DO NOT RECOMMEND KRITICAL PADS ANYMORE. Temps didn't last more than a few months and now its running hot again. I think my work was "bandaid" style with the thermal pads degrading quickly. I opened it up and the kritical pads had "sweat" a lot, with my thermal paste additions not maintaining good contact over time. Thermal putty is probably still the best. Now I'm back on the cooling quest and not satisfied with my work at all. ////
 
I may as well post my results since I found this thread so helpful. I have a 3090 ftw3 that I run nicehash on when not gaming. It was getting hot. I started out by adding fans and heatsinks to the backplate as memory junction temps were too high. I had settled on these settings to keep "cool":
 
mem +1200
gpu - 150
power 70
fans 63%
 
gpu temp 54.1c
mem junc 97.8c
hot spot 68.3c
 
Then I decided to ignore OP's advice and replace the pads. I bought the kritical pads custom set for 3090 ftw3 mentioned here. After replacing everything I had an immediate drop on mem junction to 86c, but the gpu and hotspot temps were running higher than before, especially when gaming (hot spot hitting 92c). So I went with edgeofsanity's add-paste technique and added some thermal paste (noctua nt-h1) to the top of the skinny pads on the outsides (vrm?). The photos in this thread illustrate it well. Anyways that seemed to help a lot. Potentially I did a better job with the gpu paste the second time, because using the same settings as before I get:
 
gpu temp 55.9c
mem junc 83.8c
hot spot 69.8c
 
Huge 14c drop on memory junction temps! So it ended up working out well for me with the custom-cut kritical pads and a bit of thermal paste to help bridge any gaps. It was also easy to do with these detailed write-ups. Thanks for all the info here, I can finally rest from my cooling quest.