Unable to connect to iDrac8 over SSH

The best I could find was from a thread on Spiceworks forums. The response is from a Dell representative:

There are a lot of ways to do this. You are correct that by default none of the options for a graceful shutdown are enabled, but the server will shut down if a critical threshold is met.

You can set alert actions within the iDRAC/CMC. You can set it to power off when a temperature warning or critical threshold is met. You can also set platform events or alert actions within OMSA. There is also a section in OMSA under shutdown for thermal. You can set it to perform an action there as well. Also, you can configure OMSA to execute a program if an event is triggered. You can use that feature to execute the shutdown program within Windows.

The Power Off option in the alert actions is a graceful shutdown. I recommend that you set it to shutdown on the warning threshold. If you configure it for the critical threshold it may attempt a graceful shutdown and then hit the critical limit and perform a hard shutdown before a graceful shutdown can be completed.

I also read an Official Dell PDF regarding OpenManage with this mention of thermal shutdown:

Dell OpenManage Server Administrator (OMSA) enables administrators to set temperature thresholds at which servers should perform an emergency thermal shutdown.

So the answer appears to be Yes, Dell servers do support graceful thermal shutdown and that temperature is configurable. You can use the OpenManage Server Administrator on each server to make these changes (I believe you can make these changes while the server is running). You should not need to install a centralized OpenManage management server, though it can simplify a lot of other management tasks.

:EDIT:
I should append that these answers are generic for Dell servers. I did not find anything specific to the server models you listed.

Have you tried looking at the iDRAC6 troubleshooting guide? They have a whole section of things to try for logon loops

Continual Loop

(Normally noticed when customer is trying to log into GUI Page).

1. Ensure customer is using a supported Browser

2. If customer has changed browser settings, reset to defaults and check.

3. Clear the browser cache and browser cookies and restart the browser.

4. Check the security settings of browser and the host operating system. Check the firewall settings to verify firewall is not blocking iDRAC network traffic

5. Reset iDRAC

6. Update FW/SW

7. Try draining flea power by unplugging the server from power source and then holding power button down for 20 seconds

8. Do an iDRAC reset to default using any of the following:

   a) racadm racresetcfg (No host reboot required)

   b) During POST enter CTRL+E option and execute Reset to default (Host reboot is required )

9. After reset to default is completed, reconfigure iDRAC settings (LAN config, IPMI over LAN etc.)

10. Replace parts

I've gotten these login loops before and usually the first 4 steps are enough to get me connected normally again. Usually, (assuming you haven't made changes to your browser) I start on step 3 and clear cache/cookies and can connect again about 90% of the time.