Is SQL Server 2008 R2 SP3 compatible with SharePoint 2010? Does SharePoint Server needs any additional CU
s\SPs to be installed to be in compatible with SQL Server 2008 R2 SP3
As a short answer: Yes it's supported for SharePoint 2010, no need for SharePoint 2010 SP1.
- In order to use Microsoft SQL Server 2012, you must be running SharePoint Server 2010 SP1 or a later version of SharePoint Server 2010.
- SharePoint Server 2010 is not supported on Microsoft SQL Server 2014.
Also, Check How Version support is determined by the equation in the following:
In order to maintain SharePoint and SQL Server compatibility we use the “SharePoint N-1 on SQL Server N+1” equation to determine version support. Using SharePoint Server 2010 as an example, the N release of SQL Server is 2008/2008 R2 and N+1 is SQL Server 2012. For Microsoft SharePoint Server 2013 the N release of SQL Server is 2012 and the N+1 is SQL Server 2014.
For more details check Hardware and software requirements (SharePoint Server 2010)