@Muse - This circuit upgrades the DC-DC regulator architecture into a **4-phase interleaved buck VRM** for the $+5\text{ V}$ rail and a **2-phase interleaved buck VRM** for the $+3.3\text{ V}$ rail.
### 1. 4-Phase $+5\text{ V}$ VRM (#5V)
- **Phase Staggering:** Four switching stages (#Q1, #Q2, #Q3, #Q4) are driven in quadrature with relative phase shifts of $0^\circ$, $90^\circ$, $180^\circ$, and $270^\circ$ (clock delays of $0\%$, $25\%$, $50\%$, and $75\%$).
- **Current Sharing & Thermal Relief:** The total $+5\text{ V}$ load current is split equally across four separate inductors (#L1, #L2, #L3, #L4), cutting the $I^2 R$ conduction losses per MOSFET and inductor down to a quarter.
- **Ripple Multiplier Effect:** Summing four interleaved triangular inductor currents into output capacitor #C5 multiplies the effective ripple frequency by $4\times$ ($f_{\text{eff}} = 4 \cdot f_{\text{sw}} = 200\text{ kHz}$), almost entirely canceling voltage ripple on the $+5\text{ V}$ rail.
### 2. 2-Phase $+3.3\text{ V}$ VRM (#3V3)
- **Dual-Phase Interleaving:** Two switching stages (#Q5, #Q6) operate $180^\circ$ out of phase (clock delays of $0\%$ and $50\%$) into inductors #L5 and #L6.
- **Filtering & Stability:** Doubling the effective output ripple frequency to $2 \times f_{\text{sw}} = 100\text{ kHz}$ yields steady, low-noise power across output capacitor #C3 for sensitive motherboard logic and chipsets.
### 3. $+12\text{ V}$ Input Rail (#12V)
- Filtered directly by bulk capacitor #Cin, acting as the primary DC input source for the ATX 24-pin connector and feeding the high-side MOSFETs of both VRMs.
