Question Message-Signaled Interrupts (MSI) vs INT and PCI-E GPUs


Junior Member
Feb 18, 2017
Hi. I've got a few questions about PCI-Express interrupts, because there are many misconceptions on the web regarding them. Specifically, I'm interested about PCI-E GPUs and interrupts.
Here's a short article about the advantages of MSI interrupts -

What others say about the matter:
1. MSI is ALWAYS used on PCI-E because PCI-E simply doesn't support any other interrupt method - true or false? (this is probably false because there are apps that can force MSI on a PCI-E GPU - why do they exist if PCI-E supposedly only uses MSI?)
2. This contradicts the first question: AMD GPUs use MSI by default, while nVidia GPUs use INT (INT being the older interrupt signaling method) - true or false?

Other questions:
3. How is it best to determine if MSI is active for a PCI-E GPU?
4. If it's not active - how is it best to activate it: using MSI_util_v2.exe (or other app) OR manually in Windows Registry (and how)?
5. Are there any trustworthy benchmarks of PCI-E GPUs using MSI vs INT?
6. Is there a good way to check by myself the performance of a GPU using MSI vs INT?