Repair technician finds three of four RTX 4090s were fakes packing RTX 3000-series GPUs

Why it matters: The surprisingly common practice of replacing a high-end graphics card’s GPU with a different one from a cheaper card, borking it in the process, isn’t going away. A Chinese repair technician uploaded a video to YouTube showing that of the four faulty RTX 4090 cards he recently received, three of them packed RTX 3090 or RTX 3080 dies.

The YouTuber explains in the video that the customer in this case paid 10,000 yuan ($1,392) for each graphics card, which were purchased from an overseas seller.

Taking the cards apart exposed the reason why three of them weren’t working: they were fake RTX 4090s.

Spotting that the cards weren’t packing a real AD102 isn’t easy for those who don’t know what to look for. For example, most people wouldn’t know that the QR code on this GPU is located in very bottom-left corner of the GPU substrate, whereas on the RTX 3090 and RTX 3080 GPUs, the QR code is found slightly higher. The location of this code on the first card showed the GPUs were from the RTX 3000-series. It also had fake VRAM.

The second card also had the QR code in a different location, with scarring on the die. The third card was the easiest to identify as fake as it had a green substrate and skinnier plate that looked quite different from what you would find in a real RTX 4090 – the frame wasn’t properly secured, either. One of the cards also had a protruding capacitor on the top right, which is something found on RTX 3000-series GPUs but not the RTX 4090.

Whoever made these fakes had erased the original markings on the GPUs (but not the QR codes) and engraved “AD102” on them using a laser etching machine.

the next level of the 4090 scam.

this time the surrounding mlcc position is correct, the qr code position is also correct.
however the color of the PCB substrate is too fake, and the metal frame on the substrate is not fully attached.

bilibili… pic.twitter.com/tnQMBs8zOe
– UNIKO’s Hardware 🌏 (@unikoshardware) June 14, 2025

The one bit of good news for the person who bought the cards was that the fourth one was real and could be fixed. After replacing two GDDR6X chips and some of the rear capacitors, the RTX 4090 worked.

The buyer of the cards said they would be sending the fake RTX 4090s back to the seller for a refund.

We’ve seen this scam pulled on more than one occasion. Last year, someone bought an RTX 4090 from Amazon that arrived with a “shipping damage” sticker. During the repair, it was found to have a GPU taken from an RTX 4080.

A similar case was reported this year. A gamer in China paid 3,800 yuan, or around just $530 at the time – a potential red flag – for an RTX 4090. It was sporting a GA102 GPU used in the RTX 3090 Ti, RTX 3090, and RTX 3080 Ti series, instead of the AD102.