There are only the two slots, but these will take either RDIMM (Registred) or UDIMM (Unregistred) modules, Crucial only carries the UDIMM . Please provide the Speccy Snapshot, this should tell us exactly what is installed
Please download and install Speccy to provide us with information about your computer. Clicking on this link will automatically initiate the download.
When Speccy opens you will see a screen similar to the one below.
Click on File which is outlined in red in the screen above, and then click on Publish Snapshot.
The following screen will appear, click on Yes.
The following screen will appear, click on Copy to Clipboard.
In your next post right click inside the Reply to Topic box, then click on Paste. This will load a link to the Speccy log.