Our Nano DSC refuse to do measurements after 2 years of honest work. Usually after measuring unit turning on and program starting with heating start command we clear heard the sound of relay click. But now in the same situation we hear silence. Software DSCRun 4.0.0 just after loading lead to voltage drop from 5 Volts to 2.3 Volts independent of power state of measuring unit. Relay was checked separately - it works properly from 3.9 - 5 Volt, but 2.3 V is not enough at all. Second part of software NI-DAQmx ver. 8.9.0 installed on hardware PCI-6281 card appears to have two gaps in PCI connector. AFAIK, two gaps mean universal design both to 3.3 and 5.0 Volt, but there is only one finger far from rear wall. It's evidence in favour of 5V version of PCI slot.
Though card M series is located at slot2, moving it into slot3 didn't help.
We guess PCI connector version at PC DELL OptiPlex 960 is of version 2.3.