hstm,
Thank you for the update.
Just to understand the situation:
1. Is the BIOS the latest version- 3.88 ?
2. Check in BIOS and go to I thnk Advanced > Thermal and see what it says.
3. Is the driver the correct and t latest version?
4. Are you running both the Quadro 2000 and GTX 750 at the same time?
___If so, try the system with one at time, always placing it in the PCIe x16 slot closer to the top. If the problem persists with the GTX 750 alone, then I'd recommend a replacement having a fan.
___If the problem goes away, and the system reset both cards in the system, with the Q2000 in the upper PCIe X16, go into BIOS and select the Q2000 as the primary GPU. If the fan speed is normal.
Cheers,
BambiBoom_Z