1660Ti Shunt Mod (and you should too)

[ChintzyPC]

I just successfully shunt modded my EVGA 1660Ti SC Ultra! Posting this here because it's a very uncommon mod for this GPU as of right now and I'd recommend anyone brave enough to try it themselves. Very worth it in my eyes!

Please note before anyone thinks about attempting this themselves consider that I have added a few mods to help with thermals:

• There is liquid metal on the die which should only be done if it's a copper or nickel heatsink. Mine is copper.
• GP-Extreme 12W/mK thermal pads are practically everywhere and specifically added between the back of the PCB and the backplate.
• Both GP-Extreme pads and a spare heatsink were added on the VRM's, as you can see on the left of the first photo. This was non-existent on the card at stock.

I WOULD NOT RECOMMEND DOING THIS WITHOUT SOME SORT OF MODS LIKE THESE. Most of EVGA's 1660Ti's do not come with any sort of thermal heatsink for any of the chips besides the core. I don't know if it's the same for any other cards on the market so your mileage may vary. At the very least use LM on the die and help out the VRM's somehow. If you're using watercooling with heatsinks over the VRM's you should be fine.

 

Why did I do it and you should too?

The 1660 Ti's power limit is honestly pathetic. A max of 130W with EVGA's line is very low in comparison to most other cards like it. This card *is* designed to be mid-tier and low power consumption after all. However, this is really bad when it comes to overclocking.
Under full load the core frequency severely droops purely because of this limit even on LM. When it should be hitting 2115Mhz, it's down to 1995Mhz. The core wants to go higher but it needs moar powah to do so. But the card's limit won't allow this effectively telling the core to calm the heck down. This was not kosher.
With my card I knew I could push the core further than it was limited to. Under certain loads and brief periods of time I was able to watch it stay in those higher frequencies. Not once did it artifact while it was up there. This was not a matter of the die reaching the limit of the silicon's quality.
So how does one increase the power limit on a card like this? That's where a shunt mod comes in.

 

Results:

NOTE: The thermal mods I mentioned above were used in all sets of data, both before and after the mod. Meaning these differences are purely from modding the shunt resistor only.

My max overclock both before and after is +135core and +1290mem.

Before: Max temp was 59*C. Time Spy graphics score was 6952. 45.01fps in test one. 40.1fps in test two. My frequency would droop quite a bit under load once it got demanding. Power would max out constantly to 100%.

https://www.3dmark.com/3dm/43156127?

 

After: Max temp is 72*C. Time Spy graphics score is 7125. 45.74fps in test one. 41.41fps in test two. Frequency and voltage actually stays in the max (2085-2115Mhz @ ~1.093V) through the entire load. Power is only using around 70-80% of reported total.

https://www.3dmark.com/3dm/43131116?

 

I was also able to further push the overclock to +150 on the core. (It's actually a tad bit further than this using frequency/voltage curve tweaks but that's a topic for another time) The memory did not change. This gave me an overall Time Spy point increase of 7219 making an overall 267 points gain just from a shunt mod!

https://www.3dmark.com/3dm/43239916?

 

To further make sure it worked I ran several extended cycles of Heaven, Superposition, Firestrike, Hitman's benchmark (my personal favorite since it shows particle artifacts before anything else), and played Witcher 3 and BL3 without any artifacts, hitches, frequency or voltage drops. Even Furmark ran ok maxing temps at 82*C.

 

So as we can see it was quite the success. It's using all the power it needs to keep the core clocks at a higher frequency throughout the tests. This means better performance overall. Most games got a 5-10fps gain on max settings 1080p. The temperatures went up, but that's actually a good thing since it means we know it's working. It's not close to hitting the thermal limit so it's never going to be a problem.

 

(PS: The wire's insulation looks as cruddy as it does because I had to set my iron to 500* because it was sinking heat like crazy. Couldn't melt the solder otherwise. And honestly the photo really makes the solder job look bad in general. Looks much better in person)

(Important PPS I learned elsewhere later: A direct wire shunt mod like this typically doesn't work without any resistance. The card might go into a sort of "safe" mode causing the core frequency to crash. If your card doesn't work with a direct wire then try using a resistor of low value to short it instead.

In hindsight, I wasn't using a copper wire, it was probably silver or something like that, which may have added resistance. Also, there might still be a bit of current going through the existing resistor as is so that may have helped. So with these two things in mind it may have had some sort of resistance after all and I got lucky.

However, it should be of note adding resistance may not even be required for this card at all. This mod has hardly been done so we don't really know yet. The only other user I've been able to find on the web who's done this mod did a resistor decrease as you can see here: https://www.overclock.net/forum/69-nvidia/1731568-1660ti-shunt-mod-success.html)

Edited January 23, 2020 by TheEyeOfHorus