IPMI on these servers can be really annoying at times. Here are some of the things I have come across the past few weeks:
1.) The self signed certificate is 512 bit RSA. This presents a big problem trying to open the website with a newer version of IE. If you try to connect to the web console on IE you will not have any option to continue forward. This can be fixed by opening an elevated command prompt and typing in "certutil -setreg chain\minRSAPubKeyBitLength 512". This will allow 512 bit keys, but block all keys less than 512 bits. By default 1024 is the limit (not sure when this changed, but this holds true on all my Win7 computers).
2.) AdBlockPlus on Chrome doesn't like IPMI. It will load the login page, let you login, then nothing will load. Disable ABP for that specific address should allow you to continue.
3.) Whatever browser you decide to use, make sure you allow popups on the IPMI page. When opening the Java console it will pop open a small window that launches the jnlp file.
4.) I have had no issues with Java 7, and would suggest that you use the latest version of Java for security purposes.
5.) It was posted on the previous page, but if you login to the web page, you can then manually launch the jnlp file by browsing to https://{addressgoeshere}/Java/jviewer.jnlp. Open the file, and accept all the security warnings.
6.) This is probably the biggest one I have not seen posted anywhere and took me a good bit to figure out. I had an issue on 2 nodes that were both dissimilar, but each were causing me troubles connecting to IPMI in some way. The first server would respond to ICMP, but the web interface would not load. The second server would login to the web interface, but when opening the KVM console I would face an error message that said "Connection failed." which would then close the console. To fix this issue I had to first install ipmitool on another server on the LAN (I used a 13.04 Ubuntu Server running on ESX), so it was a simple sudo apt-get install ipmitool. I then ran the command (assumes default user/pass) "ipmitool -H {IPaddress} -U root -P root shell". This should give you a shell to the IPMI showing as ipmitool>. From there I ran the command "mc reset cold" which will reset the management controller itself. After the cold reset of the controller both issues went away.
If I find anything else with the BMC, I will post it. For now these are some tips I can give. I really hope the last one helps someone, because it took a long time to figure out how to fix that. Not having direct hands on when configuring servers is a nightmare at times.