Since initial Strix Z790-E Gaming WiFi board installation, HWiNFO has always reported a significant, constantly increasing count of PCIe bus errors with Windows Balanced power option enabled. Changing the power option to High Performance or Ultimate Performance mode stopped the HWiNFO reported errors.
Windows Event Viewer identified the WHEA events as warnings of a "corrected hardware error" caused by PCI Express Root Port with primary device name A74D. Searching Device Manager did not find any system component with device name A74D, but an internet search seems to associate the device ID with the CPU. Since the same CPU installed on a Strix Z790-A Gaming WiFi D4 board does not generate any WHEA events, I decided it's another Windows nuisance alert and moved on.
Following recent installation of a 3rd NVMe drive on the Strix Z790-E board, the PCIe bus error reporting rate increased significantly while in Balanced power mode, with additional WHEA events attributed to a PCIe Root Port with different device ID.
Finally fed up with the annoyance, further internet search linked PCIe bus errors to a PCIe power saving mode called Active State Power Management (ASPM). Searching the Strix Z790-E BIOS found "PCI Express Native Power Management" enabled by default in BIOS version 1303 (also 0812, 0904 and 1202). Eureka, ...disabling the BIOS option solved the problem - no more PCI bus errors reported with Windows Balanced power option enabled.
Motherboard: Strix Z790-E Gaming WiFi (BIOS 0812, 0904, 1202 and 1303)
NVMe drives: Samsung 990 PRO 1TB, 970 EVO Plus 2TB, 990 PRO 2TB
Yes, that's the solution. Quite a lot of people have this, so nothing to be concerned about at all.