I bought a T20 (non Xeon).
I installed a Win 7 64bit OS however i know that is not listed as supported OS but the customer wanted to keep it and didn't want to buy server OS or use linux instead of W7.
Sometimes the server freezes one or two times a month. It has WD750 hdd as system disk and two 2TB WD in mirror for data. Memory upgraded with a 4GB ecc module. There is 2000VA APC UPS which supplies it and two other pcs.
I always have to do hard reset once it frezes cause it doesn't respond for any mouse or keyboard activities. I tested the memory using memtestx86. It didn't report any problem. Intel statiblity test was running two days long without any problem. When it freezes all the other pc's on the same UPS keep working. Surface tests of disk wasn't reported any problem. Sometimes it freezes during work, sometimes at night. I tried to use w8 drivers from DELL's driver site and vendors drivers for W7, Nothing changed. It still freezes. I couldnt find any clue of freezes in windows event log. BIOS event log contains nothing relevant. No BSOD just freeze mouse stop working.
I was testing it with Fedora 20 and often encountered (4 times) network problems. It just simple drops IP4 during install and normal case as well. Then worked for 3 days long without problem. I don't know if that relevant or not but i think it should not have to be happened.
Any help would be appriciated