From the Optiplex 7070 spec sheet, validated GPU cards: [IMAGE] It's not said what size your 7070 is, if you have the MT or SFF. [IMAGE] I'm just going to say I don't trust userbenchmark in this case, which makes no mention of PSU.  Even if you have the MT, a 260w PSU can't power a 120w GPU as far as I know.  It needs an additional 8-pin connection.  SFF has 200w PSU. With what's listed on the spec sheet, your 7070 needs a card that's 75w or less for the MT.  Google, or use for a search term in Amazon, etc., "dual HDMI video cards."  Find one that's 75w or less for the MT or 50w or less for the SFF. Also, if a dual HDMI card was found, it should've been linked. Dual HDMI card with 55w tdp:  VisionTek Radeon 7750 SFF 1GB DDR3 3M (2x HDMI, miniDP) Graphics Card - 900574 [URL]  Also, check your BIOS.  It might have the option to run both iGPU and eGPU.  Otherwise, normally, installing GPU card disables onboard graphics.
Please suggest me the compatible HDMI Out Graphics/Display card for Dell OptiPlex 7070, OS Windows 10 64 Bit Enterprise
HDMI Out Card