Electron Beam Powder Bed Fusion (PBF-EB) offers unique capabilities for processing high-temperature and brittle materials. Materials such as tungsten, $\gamma$-TiAl alloys, and nickel-based superalloys benefit from the high build temperatures and intrinsic preheating enabled by the electron beam, which reduce thermal gradients, residual stresses, and cracking susceptibility. However, the successful processing of these materials requires precise thermal management, as their process windows are narrow and highly sensitive to the thermal state of the part prior to melting. In PBF-EB, preheating is not only essential for powder bed stability and charge mitigation but also strongly influenced by part geometry, scan strategy, and heat accumulation at the component scale. Variations in geometry lead to heterogeneous heat dissipation and spatially varying temperatures within the build, which can significantly affect melting behavior, evaporation rates, and microstructural evolution. For example, elevated temperatures in TiAl alloys can promote aluminum evaporation, resulting in compositional shifts, ultimately affecting mechanical properties. This work proposes a GPU-accelerated approach of thermal modeling at the part-scale to enable predictive control of the PBF-EB process. While melt pool–scale models provide valuable insight into local phenomena, they are insufficient to describe the global thermal history. The part-scale thermal simulations in this work allow the assessment of geometry-dependent heat accumulation, temperature gradients, and temporal variations in preheating temperature, thereby supporting the identification of adjusted process parameters to ensure stable melting conditions within material-specific processing windows. By linking part-scale thermal behavior with material-specific sensitivities, such as evaporation, this approach provides a foundation for improved preheating strategies and process parameter selection. Ultimately, thermal part-scale modeling is a critical tool for advancing the reliable manufacturing of high-temperature materials in PBF-EB and for extending the applicability of the process to increasingly demanding material systems.