We purchased 17 Dell Optiplex GX270 workstations several years ago as part of a system installation, and immediately, we started to see issues with the units locking up; screen goes black, no response. Dell service had us pop the hood, and look at the capacitors. On all these that malfunctioned, the capacitors were bulged on top, some were leaking this cool yellow substance. Dell said it was a bad bunch of capacitors, and has been replacing the motherboards without question. We have had to replace the boards twice on several. I called into Dell yesterday, and they said it might be the heat sink fan or power supply fan. Has anyone else dealt with this, and what was determined to be the problem.