Best GPU for E8600?

Solution
The strongest will be a GTX1050ti that does not need an aux 6 pin power connector.
If your case is smaller than standard, you might need a low profile version.
You need to specify which Dell, and which size case. basically you can look in the technical manual at dell.com to see if your system has any PCIe slot power limits. But benerally GTX1050Ti. Zotac Mini is single slot and very helpful if you have one of the BTX Optiplexes.