1、功耗等级
根据《PCIx系列之“PCIe总线信号介绍”》，PCIe接口的电源包括+12V、+3.3V、+3.3Vaux三种。根据功耗的不同，三种电压的供电能力不同，PCIe卡可以分为以下几种：
10W，直接通过金手指提供；25W，直接通过金手指提供；75W，直接通过金手指提供；150W，需同时通过金手指和2×3Connector提供；225W，需同时通过金手指和2×4Connector提供；300W，需同时通过金手指和2×3Connector和2×4 Connector提供；
2、电源去耦电容要求PCIe接口的去耦电容、bulk电容要求如下：
3、电源管理PCIe卡和RC建立连接后，Link power management states有如下几种:
L0 – Active state. 是工作状态，所有的PCIe操作都可以进行。L0s – A low resume latency, energy saving “standby” state. 是节能的待机状态，但是能很快恢复到工作状态。L1 – Higher latency, lower power “standby” state. 是低能耗的待机状态，需要比L0s更多的时间恢复到工作状态。L2/L3 Ready – Staging point for L2 or L3.L2 – Auxiliary-powered Link, deep-energy-saving state. 使用辅助供电，深度节能状态，实现上面属于可选的状态。L3 – Link Off state. 是完全关闭的状态。LDn – A transitional Link Down pseudo-state prior to L0.
Device Power Management States有如下几种:D0 StateD0 uninitialized state
D0 active state
D1 StateD2 StateD3 StateD3 hot state
D3 cold state
每一种尺寸的卡，在上电时其默认最大功耗是有限制的，可以通过软件配置更高的功率。每种尺寸的卡的默认功率为：A x1 standard height, half-length card is limited to a 10 W maximum power dissipation.A x1 low profile card is limited to a 10 W maximum power dissipation.A x1 standard height, full-length card is limited to a 10 W maximum power dissipation at initial power up. When the card is configured for high power, by default, it must not exceed a 25 W maximum power dissipation oroptionally it must not exceed a 75 W maximum power dissipation.A x4/x8 or a x16 standard height or low profile card is limited to a25 W maximum power dissipation at initial power up. When a card is configured for high power, it must not exceed a 75 W maximum power dissipation. 文章转载自： 硬件助手
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