@gravejdI would have to pull up exact numbers, but based on my historical knowledge of the teams PSU would have been the favorite in 2007, 2008, 2009, 2017, and 2019. All other years PSU would have been dogs.
I can tell you that PSU definitely covered in:
2004, 2005 (straight up W), 2007, 2010 (straight up W), 2011 (backdoor cover), 2012, 2013 (straight up W), 2014, 2016 (straight up W), 2017, and 2018.
The opponent definitely covered in: 2009, 2015, 2019 (barely)
I am unsure about 2006, Michigan would have been favored but I don't recall by how much, it would've probably been right around that 7 though. Lets say that UM covered this.
I am also unsure about 2008, PSU would have been the favorite, but Illinois was ranked at the time so it likely wouldn't have been a 14 point spread. I'll say PSU covered that one.
So my estimation that in whiteout games PSU is 12-4 ATS.