The latest MIBs for this switch is version 6.3.2.7, which are included in the zipped file with the firmware version 6.3.2.7.  You can download the firmware here: http://www.dell.com/support/home/us/en/19/product-support/product/networking-n1500-series/drivers.  Unzip the file and you will see another zip file with the MIBs.  The following OIDs will show you the memory, CPU, and other information...

CPU OID
1.3.6.1.4.1.674.10895.5000.2.6132.1.1.1.1.4.9   (shows 5 sec, 60 sec., and 300 sec)

1.3.6.1.4.1.674.10895.5000.2.6132.1.1.1.1.4.1        (total free memory)
1.3.6.1.4.1.674.10895.5000.2.6132.1.1.1.1.4.2        (total memory)
1.3.6.1.4.1.674.10895.5000.2.6132.1.1.1.1.4.3        (Table for the following...)
1.3.6.1.4.1.674.10895.5000.2.6132.1.1.1.1.4.3.1.1   (Index)
1.3.6.1.4.1.674.10895.5000.2.6132.1.1.1.1.4.3.1.2   (Name of process using CPU)
1.3.6.1.4.1.674.10895.5000.2.6132.1.1.1.1.4.3.1.2   (% of  CPU used by corresponding process)
.1.3.6.1.4.1.674.10895.5000.2.6132.1.1.1.1.4.4.0     (rollup of all CPU activity)
1.3.6.1.4.1.674.10895.5000.2.6132.1.1.1.1.4.9         (CPU utilization)

Memory OIDs
 .1.3.6.1.4.1.674.10895.5000.2.6132.1.1.1.1.4.1
 .1.3.6.1.4.1.674.10895.5000.2.6132.1.1.1.1.4.2

P.S. OIDs
 .1.3.6.1.4.1.674.10895.5000.2.6132.1.1.43.1.7.1.2
 .1.3.6.1.4.1.674.10895.5000.2.6132.1.1.43.1.7.1.3

Fan OIDs
 .1.3.6.1.4.1.674.10895.5000.2.6132.1.1.43.1.6.1.2
 .1.3.6.1.4.1.674.10895.5000.2.6132.1.1.43.1.6.1.3
 .1.3.6.1.4.1.674.10895.5000.2.6132.1.1.43.1.6.1.4
 .1.3.6.1.4.1.674.10895.5000.2.6132.1.1.43.1.6.1.5

Temperature OIDs
.1.3.6.1.4.1.674.10895.5000.2.6132.1.1.43.1.8.1.5.1.0
.1.3.6.1.4.1.674.10895.5000.2.6132.1.1.43.1.8.1.5.1.1
 .1.3.6.1.4.1.674.10895.5000.2.6132.1.1.43.1.8.1.2
 .1.3.6.1.4.1.674.10895.5000.2.6132.1.1.43.1.8.1.3
 .1.3.6.1.4.1.674.10895.5000.2.6132.1.1.43.1.8.1.4

Hope this helps!

-B

any idea about mib for ssh login and logout for switch N1524