Hi,
The short answer is ''NO''
An Intel i7 9700k CPU is ''not compatible'' with the chipset on your motherboard. ''It will not work''.
According to the [https://i.dell.com/sites/csdocuments/Shared-Content_data-Sheets_Documents/en/us/Dell-Precision-Tower-3000-Series-3620-Spec-Sheet.pdf|specifications] for your motherboard it has an Intel C236 chipset.
Here’s a [https://www.intel.com.au/content/www/au/en/support/articles/000025694/processors/intel-core-processors.html|link] that states that 8th and 9th Gen CPUs are only compatible with Intel 300 series chipsets and are not backward compatible with Intel 200 series or Intel 100 series chipsets