I have several OptiPlex 9020 that I am currently trying to diagnose the same issue also.
When the machine's display turns off it sounds as though the machine is trying to start up, all fans, video card included are at full speed, but only for a moment. The noise recurs roughly every minute until it is fully awake again.
I have disconnected the DVD player to eliminate it to no avail. I had disconnected the ethernet cable and disabled the wireless wondering if possibly it was a network wake issue. I disabled IPv6 via Windows network connection management as I read some units were having IPv6 network flooding/activity issues. I disabled Intel AMT in the bios. I set the cooling fan power management to both active and passive to no avail either.
OS is Windows 7 Enterprise fully updated (as of yesterday) with most recent Bios from Dell as well as updated Intel and Radeon drivers.
Normally it is not an issue as the noise does NOT occur when the machine is being actively used. However, when silence is preferred this noise is awfully annoying as it recurs every 55-60 seconds when the display is off. Unfortunately, these are work machines with fresh Win7 Enterprise 64 bit install. I do have local admin rights to the machines, but are also managed with AD/Group Policies set at the State government level. All settings are not available to be changed or change back when Group Policy refreshes. Display off/Sleep timers are included in the GP.
I hope there is a relatively simple answer for this problem. We have over 30 of these machines in my department and several of their users have complained already. I really don't want to have to replace all of them.
