I upgraded from an RTX 3080 to a PNY RTX 5080 OC in a system with an MSI B450 Gaming Plus Max motherboard, a Ryzen 7 processor, 32 GB of DDR4 memory, and an 850 W power supply. The RTX 3080 works immediately, but the monitor reports no signal with the 5080 installed. I tested multiple HDMI and DisplayPort cables and another monitor, and the new card's fans and lighting turn on. The card is seated securely, and I removed the old display drivers before attempting to install the 5080 drivers. The 5080 uses a three-connector power adapter, while the 3080 used two connectors. I initially had two adapter plugs connected to the same daisy-chained PCIe cable, then tried separate PCIe cables, though some came from an older power supply and caused the system to click and shut off. I also tried the single native 600 W cable from the current PSU, but it made no difference. What should I check before returning the card?
3 Answers
The B450 board running PCIe 3.0 should generally still be compatible with a newer graphics card, but an old motherboard BIOS can sometimes cause initialization problems. Put the 3080 back in, update the motherboard BIOS to the latest stable version, then shut down fully and reinstall the 5080. Also clear CMOS if the system retains the wrong graphics configuration. Windows drivers are not normally relevant if you cannot get a display during startup, since the card should show an image before Windows loads.
Test with only one monitor connected and try every output on the 5080, especially DisplayPort. Confirm the monitor input is manually set to the port being used. If the 3080 works in the same slot with the same display setup, but the 5080 still gives no image after a BIOS update and correct power wiring, the card itself may be defective or the PSU may not actually meet the required transient output despite its 850 W rating.
The power cabling is the first thing I’d fix. Never mix modular cables from different power supplies, even if the plugs fit, because the pinouts can differ and can trip protection or damage hardware. Use only the cables supplied with the current PSU. If it has a native 12V-2x6/12VHPWR cable rated for the card, use that instead of the adapter. Make sure it is pushed completely into the GPU until it is fully seated, with no sharp bend right at the connector. If you use the three-8-pin adapter, each plug should ideally come from its own dedicated PCIe cable rather than a daisy chain.
Also inspect the 12V connector and adapter for any gap, scorching, bent contacts, or unusual resistance when inserting it. Don’t keep powering the card with questionable or mismatched cables; exchange the card only after the cabling and BIOS checks are ruled out.