On 16/09/2014 22:35, Valeri Galtsev wrote: > I would use riser 1. If you use riser 2, you will create more > resistance to airflow in area where already is one big heater. I > assume, there are no separators of airflow going from front to end (or > from middle where the set of fans are usually situated). My guess > would be chips facing down have much less effect on effectiveness of > cooling unless your configuration is such that airflow path along > chips (i.e. underneath that board in riser 1) is totally blocked. I concur here, my guess is to use riser 1 If it were me, I would add the temperature sensors to my monitoring and change it if I thought it was too high. If you have two servers have one in riser 1 and the other in riser 2 - Assuming the manufacturer hasn't got a recommendation or warning about using either. I would then add both to monitoring, and if there was any massive difference in temperature or perhaps even performance (not all PCI-Es are the same) then I would schedule a maintenance window to swap one of the cards in one of the servers after deployment. -- Regards, Giles Coochey, CCNP, CCNA, CCNAS NetSecSpec Ltd +44 (0) 8444 780677 +44 (0) 7584 634135 http://www.coochey.net http://www.netsecspec.co.uk giles at coochey.net