MSI (Message Signaled Interrupts) mode is a Windows feature that allows hardware like GPUs to communicate with the CPU more efficiently by using memory writes instead of dedicated hardware interrupt lines. Introduced with PCIe 2.2 and implemented in Windows Vista, MSI reduces interrupt collisions and can improve frame pacing and input latency on older systems. However, it does not increase average frame rates or raw GPU speed.

Modern drivers for cards like the RTX 5090 enable MSI by default, and forcing it on hardware where manufacturers disabled it can cause instability, crashes, or device unresponsiveness. MSI-X, introduced with PCI 3.0 in 2010, extends this capability and is now the default in Windows 10 and 11 when available. Manufacturers control MSI via the MSISupported registry value, and overriding their settings risks compatibility issues, as seen in cases involving certain SSDs and StorAHCI.sys drivers.

For actual performance gains, upgrading hardware is more effective than tweaking MSI settings.