To add to your comments, the 4 beeps RAM error may indicate there's a problem with RAM elsewhere, not just on the motherboard. Add-in cards, including video cards, typically have their own RAM, so your 4 beep error may have  accurately detected a RAM failure on the USB card, not with system (motherboard) RAM.
XPS 8300 4 beeps. I see the most common answer posted here deals with memory. My four beeps had nothing to do with memory. When I ran the basic test offered at boot up on the system it immediately complained about "USB Cable #3". Hoping it was complaining about a device plugged in to one of the USB ports I pulled them all out. Even then the basic test on a boot failure said the same thing, a problem with "USB Cable #3". At this point, there was only one USB cable to unplug. I've had for several years a 5 port USB 3.0 card I had added that has worked fine, but I unplugged the power to it (if that hadn't worked I'd have unplugged the USB 3.0 card itself). Removing the power from the USB 3.0 card eliminated the problem. So, right now I booted and posted this on that boot. I'll replace the card and be back in business. So, four beeps can have another meaning. I should add this is not an error on Dell's part, when my machine rolled off their line there was no such thing as USB 3.0, and certainly no after-market cards to upgrade this PC to 3.0. It's to Dell's credit this machine still performs well. It's powerful processor an SSD drive, a separate video card with it's own CPU have kept me up with the times. I did have to stop Microsoft updates to Windows 10 Pro last June, because Microsoft is no longer trying to serve the XPS 8300 and it's CPU family, etc. However, I'm content as is, so no complaint, just praise to Dell for a good machine to begin with and one that accepted hardware changes/add-on's that kept me in business. I'm not asking for any help from the community I just wanted to share this info in case someone has a similar 4 beep problem, they'll know what it is and how I fixed it. The card I bought was not only inexpensive (under $20) not only gave me 5 extra USB ports at 3.0 (which sped things up) it ran fine until it didn't, which was at least several years. I'll install it's replacement today.
XPS 8300, 4 beeps not involving memory