According to the beep code chart I have, four beeps is a memory problem. With the PC powered off, open the case and "reseat" each memory module, then power on and see if it makes a difference. If reseating does not help, remove all but one memory module then try that. If it still does it, remove that memory module and try another.
Reseat - Remove each memory module one at a time then reinstall making sure the module is fully and correctly seated.
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Dell forum member since 2002
Dell Inspiron 15 - 5577 Laptop
Home Built Desktop PC with ASUS ROG Z170, i7 6700K CPU
Windows 10 64 bit Pro and Windows 10 Insider Program Beta Versions. SSD drives. Cakewalk by BandLab and Studio One 4.1 Recordng Studio Software.