When Im Stability testing I just use the temp for the core on the Kombuster main screen.
MSI Kombustor 2.0.1 Maintenance Release - 3D Tech News, Pixel Hacking, Data Visualization and 3D Programming - Geeks3D.com
BTW, Kombustor is the best Burn-in Stability tester out there.
GPUz is a probably one of the better ones for temps monitoring. It gives you temps and voltages on 1 simple to read tab.
GPU-Z Video card GPU Information Utility