MSI Mode for GPU (MSISupported): Should You Enable It?

Should you force MSI mode on your graphics card?

MSI mode switches how a device tells the processor it needs attention, from an interrupt line to a message written to memory. Windows reads a registry value under the device's hardware key to decide whether to use it, and Microsoft documents that value as something a driver's installation file sets, not as a user tweak. Forcing it on is often suggested for DPC latency, but it only makes sense when a specific device has been shown to be the cause.

Registry location and values

MSISupported

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\PCI\<device>\<instance>\Device Parameters\Interrupt Management\MessageSignaledInterruptProperties
Value name: MSISupported
Type: REG_DWORD
Default: Whatever the device's driver installation file sets; there is no single Windows default

Value	What it does
`1`	The device uses message-signalled interrupts, provided the device and driver support them.
`0 or absent`	The device uses line-based interrupts.

MessageNumberLimit

Location: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum\PCI\<device>\<instance>\Device Parameters\Interrupt Management\MessageSignaledInterruptProperties
Value name: MessageNumberLimit
Type: REG_DWORD
Default: Set by the driver, if at all

Value	What it does
`1, 2, 4, 8 or 16`	The maximum number of messages for PCI 2.2 message-signalled interrupts.
`Up to 2048`	The maximum number of messages for MSI-X.

What Windows actually does with this

Line-based interrupts use a physical or virtual interrupt line that a device signals until the processor responds, and several devices can end up sharing one line. Message-signalled interrupts, introduced in PCI 2.2, replace the line with a value the device writes to a memory address, and MSI-X, added in PCI 3.0, allows far more messages per device. When a device and its driver support both, Windows uses MSI-X automatically. The MSISupported value tells Windows whether a device should use message-signalled interrupts at all, and Microsoft documents it as being written by the driver's INF file during installation.

What it affects

How one device's interrupts reach the processor. It changes nothing about rendering, the driver's other settings or any game, and it makes no difference on a device whose driver already enables message-signalled interrupts.

Is it worth changing?

Not a general performance tweak. Microsoft does not document forcing MSISupported as a user optimisation, and neither Microsoft nor NVIDIA publishes guidance that forcing it on a graphics card improves games. It is reasonable to try only when a tool such as LatencyMon identifies the graphics driver as the source of high DPC latency and the card is not already using message-signalled interrupts. If nothing measurably improves, set it back.

What can go wrong

Forcing message-signalled interrupts on a device or driver that does not handle them properly is outside what Microsoft documents, so the failure modes are not officially described. Because the value sits under a hardware instance key, reinstalling the driver or moving the card to another slot can also create a new instance that no longer carries the forced value.

How to undo it

Delete MSISupported, or set it back to the value the driver originally wrote, then restart. To find the right key, open the device in Device Manager, choose the Details tab and select Device instance path. If the device stops working but Windows still starts, make the change from Safe Mode.

Create a System Restore Point before editing the registry. Every setting on this page is reversible, but a restore point is the difference between undoing one change and reinstalling Windows.

Which Windows versions this applies to

Windows 10 and Windows 11, for PCI and PCI Express devices whose drivers support message-signalled interrupts.

MSI mode for the GPU (MSISupported): common questions

How do I find my graphics card's device key?

In Device Manager, open the graphics card's properties, choose the Details tab and select Device instance path. That path, under HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Enum, is the hardware key that holds the interrupt settings.

Is MSI mode related to MSI Afterburner?

No. Here MSI stands for message-signalled interrupts, a way hardware signals the processor. MSI Afterburner is a monitoring and tuning tool from the hardware company MSI, and the two have nothing to do with each other.

Why is Enable MSI Mode for GPU labelled High Risk in JINSHI?

Because forcing it goes beyond what Microsoft documents for end users and can cause problems on hardware that does not suit it. It is not in the app's recommended set, and it should only be tried when the graphics driver has been shown to cause DPC latency.

Can a driver update undo a forced MSI setting?

It can. A driver installation can write the device's interrupt settings again, and a new driver or a different slot can create a new device instance, so check the value after updating the graphics driver.

Sources

Does JINSHI Tweaks change this?

This page documents a setting that corresponds to the following toggle in JINSHI PC Tweaks: Enable MSI Mode for GPU.

The reference above is written to be usable without the product. Everything here can be applied by hand for free. What the application adds is that the change is applied in one pass, the original value is stored first, and each toggle can be reversed individually. PC Tweaks does not create a System Restore Point for you, so make one before the first run. The JINSHI Tweaks homepage explains what the four apps include.

What JINSHI Tweaks changes

Related settings

Guides that cover this setting

Every change JINSHI PC Tweaks can make is listed on the complete tweak list, and the product itself is described on PC Tweaks for gaming.

MSI mode for the GPU (MSISupported)