We did the same several years ago. At the time I found http://www.cs.toronto.edu/~bianca/papers/temperature_cam.pdf quite interesting. I didn't find many other precise papers about issues when running at a higher temperatures, but many "should" and "can".

Based on ASHARE there are two guidelines from HPE and IBM: https://www.chiltrix.com/documents/HP-ASHRAE.pdf https://www.ibm.com/downloads/cas/1Q94RPGE

We found (by measurement) that some places in the datacenter with suboptimal airflow are well over the average or simulated temperature so one can leave the safe temperature envelope if one isn't careful.