if it hangs before Windows page, if it takes forever on Dell or AW logo page with progress bar not moving to end, it is stalling in POST, suggesting one piece of hardware not passing test.  This is before you get to the pre-boot stage.  it does not sound like a psu issue so far. Does your bios complain that there is a checksum error or date/time is incorrect?  Those would be symptoms of bad CMOs battery.  BSOD is non specific and can be due to motherboard chipset or memory instability.   I had a Dell non-AW pc that intermittently refused to POST and needed repeated CMOs jumper resets.  Just a note that motherboard does get old and fall more frequently depending on model.
Hi. My first time posting on here. I've owned an Alienware X51 R2 since 2014 and it has worked a dream until recently when it has become somewhat unreliable 1. Sometimes when booting it hangs before getting to the Windows start up screen - turning it off and on generally fixes the problem but I'm wondering if this is symptomatic of some other issue? 2. Three times this year I've seen a blue screen of death, after which the machine refuses to boot. I've followed advice on the Dell forums to reset the CMOS by moving the jumper. This works, but as this has now happened 3 times I'm wondering if there is a root cause that I can fix? Should I change the CMOS battery, is it a PSU issue or some other cause? In case it helps the specs are:i5-4460 processor (6MB Cache, up to 3.4GHz)8GB Dual Channel DDR3NVIDIA(R) GeForce(R) GTX 745 with 4GB DDR3240W power supply Any help/advice gratefully received. Thank you!
X51 R2 Unreliable Boot