I'm running a Dell with a Core 15 and a 250 graphics card. I can link 2 more monitors off a dock without issue. I can link/run a third monitor without the dock (HDMI to DVI) but I fancy I'm loosing a little clarity etc. Would any body know if this is possible.
Unless at least one of these monitors is connected via USB 3.0, you cannot use 4 monitors. The Intel HD Graphics engine built into your processor only has support for up to 3 monitors.
Well, let me qualify my answer this way: Presuming that you already have three monitors working, you can add a fourth monitor using a USB 3.0 adapter.
I purchased this one: https://www.amazon.com/gp/product/B06Y681RPY Amazon.com: USB 3.0 to HDMI/VGA/DVI External Video Card, which will actually let me to connect one or two monitors (though I haven't tried using this extra capability as yet).