On the VMware system, you can see the alert of the hardware status as below:
Please check the picture above.
1. Login the ESXI with "VMware vSphere Client", we can check the health status of the memory, which is normal
2. Collect the event log of the BMC, we find there is no abnormal about the momory currently.
And we found that there are alarms about the "Assert" and "Deassert" for the alerted memory.
According to the http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=2070667
We can see there is a bug for VMware 5.1 as the picture below about "Assert" and "Deassert"
We have to do the patch from VMware to fix it according to his anouncement. Or, because it is a fake alert, we can ignore it.