Based on the information you provided, it looks like the Dell PowerEdge R910 server you have is compatible with both 4GB and 8GB memory modules. However, it's always best to check with the manufacturer to ensure compatibility. The memory part number you listed, M393B1K70DH0-YH9, is a 240-pin DDR3 ECC Registered DIMM module with a speed of 1333 MHz. This module should be compatible with the PowerEdge R910 server, but it's important to verify this with Dell to ensure compatibility with your specific configuration.
Hi again Support  I have one host model PowerEdge R910 with CPU 16 CPUs x Intel(R) Xeon(R) CPU E7520 @ 1.87GHz  VMware is 6.0.0 Update 3 (Build 7967664)  now we are using memory 4 GB * 64 slot part# is “M393B5273CH0-CH9”  we plan to upgrade to 8 GB * 64 part#   M393B1K70DH0-YH9 just I need your confirmation if this part is compatible with our host server, to start upgrading.  I wait your confirmation pls.   
Dell R910 Memory Upgrade