Modder pushes RTX 3080 Ti 20GB engineering sample to 555W
© ChintzyPC A modder has published an update on an unreleased GeForce RTX 3080 Ti Founders Edition engineering sample with 20GB of GDDR6X. The card is described as a hybrid design with a 320-bit memory bus and rear memory placement similar to RTX 3090-style layouts. Like the earlier reports around this model, the card still relies on an unofficial patched-driver approach for normal operation. In other words, this is not an official SKU, rather a card that somehow ended up in enthusiast hands.
We covered this 20GB RTX 3080 Ti sample earlier when its teardown and benchmarks were shared, including the claim of GA102-250 labeling, the 320-bit configuration, and performance landing closer to RTX 3080-class results under a conservative power limit. The new update focuses on lifting power limits and then reworking cooling to stop throttling and instability once the card is allowed to draw more power.
© ChintzyPC Apparently, the modder was busy and he says he performed a stacked shunt mod using 10 mOhm shunts on the 12-pin and PCIe slot sense rails, leaving memory and controller sense untouched. They report the stock limit was about 390W, stock behavior after the mod reached about 480W actual draw, and brief peaks hit around 555W with a stable overclock. They also claim they monitored connector temperatures with a thermocouple and note some load is distributed through the PCIe slot.
© ChintzyPC 
© ChintzyPC After lifting power limits, they report the GPU core began heat soaking and throttling, so he switched to liquid metal on the die and increased mounting pressure using 0.5 mm clamp washers. They also swapped thermal pads from 12W/mK to 20W/mK. The modder reports idle temperatures around 31°C and says core throttling stopped after the contact-pressure change.
The remaining issue was memory temperature, which the modder links to the cooler mismatch, a 3080 Ti cooler and shroud paired with a PCB carrying rear memory modules. They report memory junction temperatures reaching 100°C to 102°C under sustained load, with artifacts, before adding external heatsinks to the shell plus a dedicated fan, stabilizing around 94°C under heavy ray tracing load.
Using the same overclock settings as before, he reports higher 3DMark scores, including Speedway 5492 (from 5403), Steel Nomad 5338 (from 5155), and Port Royal 14337 (from 13947).
Props to Chintzy for trying. I would never risk destroying an engineering sample of a never released card, especially one of the few known to exist.
Source: Reddit
