If you've been in PC building and the electronics world for long enough, you'll know that
kapton tape solves a lot of problems. This time around, it's to fix an incompatibility between NVIDIA RTX 50 series cards and some EVGA Z690 motherboards (and possibly Z790 as well) that causes the system to not boot entirely.
The specific incompatibility revolves around pins 5 and 6 of the PCIe slot. According to the PCIe specification, these are used for SMBUS communication for exchanging information between the device and the motherboard. Almost no consumer-grade add-in cards use these pins, so motherboard manufacturers don't bother hooking them up. In the server world, they're used mostly for out-of-band management.
EVGA, however, did wire those pins in select motherboard models, and the GeForce 50 models (more specifically, a GeForce RTX 5080), fail to start up when it hears chatter from those pins. This information comes by way of a Reddit thread where user MurkyIncident explains his workaround: just taping those pins over with kapton tape, after diligent preparation by cleaning them with isopropyl alcohol first. Although any kapton tape will do, he recommends Thermal Grizzly's, as it comes in sheets rather than rolls, making it easier to cut a 2mm slice with precision.
Dell network card with electrical tape over pins 5-6 so it would work in a desktop system. Source: HP Forums.
At first sight, it'd be easy to blame EVGA's departure from the GPU market in 2022 and the subsequent closure of most of its operations as an indirect root cause, as the company's technical support is reportedly sparse and delayed. However, it's hard to fault a motherboard for following the PCIe spec to the letter. It's not an unknown fact that some server-grade cards fail to work in consumer mobos precisely because they’re missing SMBUS.
In fact, in that very same Reddit thread, a user who's apparently in touch with the NVIDIA driver team has asked MurkyIncident for additional info to pass on, signaling that it could be the RTX card's firmware at fault. While it's not impossible that the motherboard may be speaking SMBUS gibberish, that scenario is the least likely one. Anyway, if you’re affected by this, then at least this DIY fix is rather cheap and easy.
