The new NVIDIA GeForce RTX 5090 is the first high-end graphics card that makes use of a PCI-Express 5.0 bus interface. Are you in trouble when try to run it on PCIe 4.0? What about x8, like when an SSD is using up some bandwidth? We’ve also tested various PCI-Express 3.0, 2.0 and 1.1 configs to get a feel for how FPS scales with bandwidth.
Tl;dr: You lose about 1% of performance going from PCIE 5.0 x16 to 4.0 x16.
x16 4.0
Remember what we said about PCI-Express 5.0 x16 availability being spotty on mid-range platforms? This makes it crucial for us to see how the RTX 5090 performs on PCI-Express 4.0 x16. Since LGA1700 processors don’t put out a dedicated Gen 5 NVMe connection, Intel’s motherboard partners resorted to wiring out M.2 Gen 5 NVMe slots by subtracting lanes from the Gen 5 x16 PEG interface, reducing it to PCI-Express 5.0 x8, which is exactly the same bandwidth as PCI-Express 4.0 x16—an invaluable data-point for the RTX 5090. We are happy to report that performance loss in this mode is well contained, and you lose about 1% performance, across all three resolutions. There are barely any outliers to report about from our set of game tests.That’s basically within the margin of error. It seems that for gaming on dGPUs, the PCIE 5.0 vs 4.0 isn’t really that important.
Meaning, since PCIe5 Mini-ITX boards still have a very limited selection and are still very expensive, i’ll be going with a 4er board in my future-proof gaming-sffpc. Btw, that with 1% was a year ago already, so no progress there.
Good to know that PCIe 2.0 x16 respectively 3.0 x8 is still enough for pretty much anything less than a 5090 class card. Except for specific, comm heavy workloads maybe
Gamers Nexus has done their own, seemingly similar testing (I haven’t watched it): https://youtu.be/L1NPFFRTzLo
