Seems to be a rather popular question of recent.
Here is the official temperature range for an operating AlphaServer ES45 box:
50° to 95° F (10° to 35° C)
This range from the official source for this stuff:
http://h18004.www1.hp.com/products/quickspecs/10994_div/10994_div.PDFAlso see the other recent discussions in:
http://forums13.itrc.hp.com/service/forums/questionanswer.do?threadId=1333707IIRC, there are others.
Or check the technical specs and the service guide for the box, or the QuickSpecs or Systems and Options Catalog (SOC) for this stuff. This is the specified environmental conditions, and the best spot for these details.
Depending on the gear, look around these sites:
http://www.hp.com/go/productbulletinhttp://docs.hp.com/http://vt100.net/manxFor those folks here that work for HP in various capacities, there are almost certainly internal resources and libraries with details on the various servers and server environments.
Or as was mentioned, you can view the current thresholds with the RMC. Here's a write-up on the RMC for the AlphaServer ES40 series that will give you a feel for what is available and how this stuff works:
http://labs.hoffmanlabs.com/node/445I do not tend to recommend use of the RMC value as the operating environment. Stay within the published environmental values for operating and storage, for humidity, and rate of change. If you're at shutdown, you're already outside the published temperature range.