If you are not comfortable doing such things and/or you do not have a multimeter then find a knowledgeable family member or friend to help.
Thanks for the link but this applies to regular PSU's, not the FLEX Hot PLUG ones. Or do I need to plug back the PSU and test it using the cables attached to the Workstation? And yes, I've used a multimeter to test PSU and I have a PSU tester too.