The defender was highly impressive for the Eagles last season after joining from Liverpool in January and both he and chairman Steve Parish have suggested they want to work out a permanent move this summer.
The France international does not have a future at Liverpool as things stand after falling out with Reds boss Jurgen Klopp last summer, but a stumbling block over a possible full-time Palace switch is the fact the Reds want £30million for him.
De Boer says he wants to run the rule over all the players he has inherited at Selhurst Park and will take his time to decide if a deal for Sakho is worth pursuing.
He said: “He was certainly impressive and important last season, but we will look at what we need. First of all I need to see all the players and get a good opinion on them. I know a lot about the team, but it’s different when a new manager comes in.
“Already I have my opinion, but I need to see them live to see if my opinion changes.”