Am4 Pinout (2025)

Corner with triangle marker (missing pin) is key. Row A: A1 (VDD18) A2 (VDD) A3 (VDD) A4 (VSS) ... Row B: B1 (VDD18) B2 (VDD) B3 (VSS) B4 (VSS) ... Row C: C1 (PWR_OK) C2 (VDD) C3 (VDD) C4 (VSS) ... ... | Feature | AM4 (PGA) | AM5 (LGA) | |---------|-----------|-----------| | Pins on | CPU | Motherboard | | Pin count | 1331 | 1718 | | DDR type | DDR4 | DDR5 | | PCIe | 3.0/4.0 (CPU dependent) | 5.0 |

| Lane Group | Destination | |------------|-------------| | | Primary PEG (PCIe x16 slot) | | Lanes 16–19 | M.2 NVMe (direct to CPU – “M2_1”) | | Lanes 20–23 | Chipset (downlink – PCIe 3.0 or 4.0) | am4 pinout

Do not confuse AM4 pinout with AM5 – they are mechanically and electrically incompatible. If you need a (e.g., “What pin is VDD_SOC on AM4?”), please provide the motherboard or CPU model, as actual routing varies. For most repair or modding purposes, board-level schematics are required. Corner with triangle marker (missing pin) is key

Here is the technical content regarding the (the socket used for AMD Ryzen CPUs, including 1000 to 5000 series, and some 4000-series APUs). Note: The AM5 socket (Ryzen 7000+) uses an LGA design and has a completely different pinout. The following applies only to AM4 (PGA – Pin Grid Array). 1. Basic Specifications | Feature | Detail | |---------|--------| | Type | PGA (Pin Grid Array) – pins are on the CPU | | Pins | 1331 pins (often referred to as Socket AM4, 1331) | | Pin Arrangement | 32×32 grid with missing pins in central area | | Pitch | 1.0 mm | | Keying | One corner has a missing pin (triangle marker) | Key fact: Despite having 1331 pins, many are VSS (Ground) or VDD (Power) for signal integrity. 2. Pin Groups (Functional Categories) The pins are divided into these major groups: Row C: C1 (PWR_OK) C2 (VDD) C3 (VDD) C4 (VSS)

| Signal | Description | |--------|-------------| | DQ[0..63] | Data lines | | DQS[0..7]_P/N | Data strobe (differential) | | CA[0..9] | Command/address | | CS#[0..3] | Chip select | | CKE[0..1] | Clock enable | | VDD_MEM | DRAM power (1.2V) | | VPP | DRAM programming voltage (2.5V) | AM4 CPUs (except APUs) provide 16+4+4 PCIe lanes:

| Group | Function | Approx. Count | |-------|----------|----------------| | | CPU core voltage (VCore) | ~200–250 | | VSS | Ground | ~400–500 | | VDD_SOC | SoC / Uncore voltage | ~30–50 | | VDD_MISC | Miscellaneous logic | ~10–15 | | VDDP | DDR PHY voltage | ~10 | | VDD18 | 1.8V standby | ~5 | | DDR4 channels | Memory data/address/control | ~200 | | PCIe lanes | PCIe 3.0/4.0 (depends on CPU) | ~160 | | FCH (chipset) | Promontory chipset link | ~30 | | SATA / USB / GPIO | I/O | ~20 | | Clocks & reset | CLK, PWR_OK, RESET# | ~10 | | SVI2 | Serial Voltage Identification (power management) | 2 | | JTAG / debug | Test/debug | ~10 | 3. Important Pin Signals (Examples) Here are some commonly referenced pins for troubleshooting, modding, or voltage measurement: