Apparently AMD has seen fit to drop a “Hotfix” driver for Vega today to fix:

An intermittent crash issue may be experienced on some Radeon RX Vega series graphics products.
You can read the full release notes here, as well as get Win10 64-bit drivers here, and Win7 64-bit here. Thanks cageymaru!
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Source: [H]ardOCP – Radeon Software Crimson ReLive Edition 17.11.3 Radeon RX Vega Hotfix