Why AMD AM4 CPUs Have Pins but AM5 Does Not: PGA vs LGA, Compatibility and Safe Installation

PGA vs. LGA: where the pins are​

Both designs make the same electrical connection between processor and motherboard. What differs is which part carries the delicate metal.

• AM4 (PGA, pin grid array): The pins are small metal spikes on the underside of the CPU, exposed and vulnerable as soon as you pick the chip up. One guide puts the count at 1,331 pins.
• AM5 (LGA, land grid array): The pins live inside the motherboard socket, and the CPU has flat gold contact pads instead. The socket is LGA 1718, with 1,718 contacts.

AMD launched AM5 with Ryzen 7000 on September 27, 2022, after announcing it on August 29, 2022. Tom's Hardware noted at the time that AM5 was AMD's first move to LGA on its mainstream platform, after using PGA for ages. AMD had already used LGA on higher-end parts. Socket TR4 was its first consumer LGA socket, for Ryzen Threadripper.

So the headline's premise is slightly off. AMD's mainstream desktop chips moved away from pins. The pinned chips you can still buy are AM4-era parts.

Why did AMD stay with PGA on AM4?​

I couldn't find an AMD statement explaining why AM4 used PGA. The story that PGA kept motherboard costs down is plausible, but I can't confirm it as AMD's reasoning.

Some engineering context is documented. AMD adopted LGA for its high-pin-count server sockets because a 1,944-pin PGA would have been too large for most motherboards. That is a size argument for server parts, not an AM4 cost argument. Treat it as background, not AMD's reason for AM4.

Compatibility: AM4 and AM5 don't mix​

The two sockets are not interchangeable, and the BGR piece itself says the move broke backward compatibility. XDA Developers lays out the split like this:

That table predates later AM5 generations. A MaxMyBuild guide lists AM5 as covering Ryzen 7000–9000, and Wikipedia also lists the Ryzen 8000 series on AM5.

Memory differs as well. AM5 supports DDR5, which AMD's launch announcement describes as dual-channel DDR5 with up to 24 PCIe 5.0 lanes. AM4 uses older DDR4, which BGR says is generally cheaper. Before you buy, check that the exact CPU appears on your motherboard's support list, and check what BIOS version it needs. I didn't find a full AM4 compatibility table to reproduce here.

Installing without bending anything​

The core rule is the same for both sockets. A zero-insertion-force socket never needs force. If you feel resistance before closing the lever, the CPU is misaligned, not stuck.

AM4 (pins on the CPU)

1. Ground yourself to discharge static.
2. Open the socket arm fully. A guide from ApexGear warns that a half-open arm leaves the holes partly obstructed, which could bend pins.
3. Hold the CPU by its edges. Touch only its sides, and avoid touching any pins on the motherboard or CPU.
4. Match the small triangle on the CPU to the one on the socket. The two triangles are usually in the bottom left corner.
5. Set the CPU down so it lies flat without pressure, then lower the arm. Lower it completely to hold the CPU in place.

AM5 (pins in the socket)

1. Release the load lever. Tom's Hardware describes MSI's walkthrough: push the lever down to release the load plate.
2. Pick up the chip with thumb and index finger, line up the two socket notches (one on each side), and gently lower the processor into the socket.
3. Lower the load plate and return the lever to its original position. The protective cover pops off by itself.

Don't pry the cover off. Sportskeeda notes that users do not need to touch this cover, because it ejects itself once the processor is installed.

Moving the pins to the motherboard doesn't make them safe. Sportskeeda says LGA sockets are easier to handle, and a bent pin is fairly unlikely compared with PGA. The risk is lower, but it's still there. A bent socket pin means a damaged board, and a bent PGA pin means a damaged CPU. Even so, failing to line up the notches correctly could potentially damage the system.

Claims in the BGR piece I'd treat carefully​

BGR says misaligned pins cause data corruption, electrical hazards and overheating. I found no documentation of those specific outcomes. A bent or damaged contact can stop the CPU making a reliable connection, and the result depends on which contact is hurt. BGR also describes the pins as being about power delivery. They carry signals as well as power.

Its claim that AI-driven shortages are pushing builders back to AM4 is plausible, but I found no market data for it, so I'm not repeating it as fact. BGR's advice to avoid used CPUs is also an opinion, not a finding. The practical point for used AM4 chips is simple: inspect the pins before you buy, or ask the seller for close-up photos.

Bottom line​

• AM4 puts pins on the CPU, so the processor is the fragile part.
• AM5 puts them in the motherboard socket, so the board is the fragile part.
• The two sockets aren't compatible, so match the CPU, board, memory type and BIOS before buying.
• Install with no force, keep your fingers off the contacts, and stop if anything resists.