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 Z170, i7 6700K CPU
Windows 10 64 bit Pro and Windows 10 Insider Program Beta Versions. SSD drives. Studio One 3 Recordng Studio Software.