We've seen a few unreleased Nvidia GeForce RTX 3080 Ti graphics cards with 20GB VRAM appear in the wild, with one engineering sample popping up just before the holidays last year. Another Redditor who just happens to have one in their repertoire of tech isn't treating this rare GPU with kid gloves, however. They've gone all-out by modding the card to "see what the actual limits of [its] design" are after initially replacing the thermal paste and heatsink pads on the GPU die earlier this month.
This is a bold and brave experiment, shared in full detail on Reddit, that explains both the rationale and the results. The user, ChintzyPC, explains in an earlier post that they'd acquired the card from a friend who had bought two identical engineering samples for $200 apiece, although their "friend" charged them $700 for the spare. Like earlier samples we've seen online, this GPU features the same Founders Edition shell, with a boost in VRAM from 12GB in the released model (which we reviewed back in 2021) to 20GB, although with a narrower 320-bit memory bus compared to the original model.
While they'd initially discounted the possibility of modding the GPU due to its rarity, suggesting that it "didn't feel worth the risk," just over two weeks later, they've reversed course and gone all-in. Their first port of call was a "proper stack shunt mod," using 10 mOhm shunts to increase the power draw from a stock limit of approximately 390W to around 480W for stock, peaking at around 555W with "stable" overclocking applied. ChintzyPC explains that "some load is distributed through the PCIe slot." Arguably, however, this modder is pushing this GPU close to its power limits through its 12-pin cable.
The next step, according to ChintzyPC, was dealing with cooling. With the power shunts in place, the GPU die started to see heat soaking, where more heat is absorbed than can be dissipated, and with inevitable performance throttling. To compensate, they switched to liquid metal cooling, using clamp washers to increase mounting pressure after the cooling attempt initially failed. This dropped idle temps to "around 31C" with no further throttling.
The PCB's unusual design caused some issues, however. According to ChintzyPC, the sample used the standard 3080 Ti cooler and shroud, but with added memory on the back in a way that the cooler wasn't designed to cool (this was an engineering sample, after all). Heavy testing saw this memory rise in temperature to around 100°C, with artifacts appearing on screen from the instability. After a few failed attempts with improved pads and an added fan, the curious modder applied extra, external heatsinks to the shell, along with an extra fan to blow cool air across, bringing memory junction temps down to around 94°C under heavy loads.
The end result is a GPU with performance that is "still a weird hybrid of a 3090 PCB, 320-bit bus, and 20GB config," according to ChintzyPC, although now with mods that allow it to bypass the "heavily power and thermally constrained" nature of the original sample piece. Working with a patched driver, this Frankenstein card is now ready to behave "much more like the 3080 Ti class GPU it should have been," according to them.
Is this worth doing? If you're one of the rare few with an unreleased 20GB RTX 3080 Ti engineering sample and the technical know-how to put it together, you might be tempted. As ChintzyPC themselves say, this was "mostly for the sake of experimental exploration." In reality, a GPU like this isn't going to have much practical value outside of a serious collector anyway, although with GPU prices so high, I'd still be sweating before I went at it with a soldering iron. With so few samples likely still intact, I can only commend their bravery in risking $700 to answer one simple question: how far can a GPU like this be pushed?
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