Am Tue, Sep 19, 2023 at 09:17:45AM -0400 schrieb Rich Freeman: > > Well they allow you to put larger cards in, but they don’t have the lanes > > for it. Somewhere else in the thread was mentioned that the number of lanes > > is very limited. Only the main slot (the big one for the GPU) is directly > > connected to the CPU. The rest is hooked up to the chipset which itself is > > connected to the CPU either via PCIe×4 (AMD) or whatchacallit (DMI?) for > > Intel. > > So, on most AMD boards these days all the PCIe lanes are wired to the > CPU I believe.
Not all. Only the main slot. The rest is routed through the chipset. I’m only speaking of expansion slots here. But for NVMe it is similar: the primary one is attached to the CPU, any other is connected via the chipset. This is for AM4. AM5 provides two NVMes. > The higher-end motherboards have switches, and not all > the lanes may be the highest supported generation, but I don't think > any modern AMD motherboards have any kind of PCIe controller on them. Here are the I/O capabilities of the socket: https://www.reddit.com/r/Amd/comments/bus60i/amd_x570_detailed_block_diagram_pcie_lanes_and_io/ A slight problem is that it is connected to the CPU by only 4.0×4. So tough luck if you want to do parallel high-speed stuff with two PCIe×4 M.2 drives. > Basically memory, USB, and PCIe are all getting so fast that trying to > implement a whole bunch of separate controller chips just doesn't make > sense. However, the CPU has a limited number of them, hence there are more in the chipset. Most notably SATA. > > Look for youself and filter what you need, like 1 or 2 HDMI, DP and PCIe: > > AM4: https://skinflint.co.uk/?cat=mbam4&xf=18869_4%7E4400_ATX > > AM5: https://skinflint.co.uk/?cat=mbam5&xf=18869_4%7E4400_ATX > > Interestingly: the filter goes up to 6 PCIe slots for the former, but only > > to > > 4 for the latter. > > You can definitely get more PCIe slots on AM5, but the trend is to > have less in general. Those look really weird. “Huge” ATX boards, but all covered up with fancy gamer-style plastics lids and only two slots poking out. > Look at the X670 chipset boards as those tend to have PCIe switches which > give them more lanes. The switched interfaces will generally not support > PCIe v5. The X series are two “B-chipset chips” daisychained together to double the downstream connections. Meaning one sits behind the other from the POV of the CPU and they share their uplink. Here are some nice block diagrams of the different AM5 chipset families: https://www.hwcooling.net/en/amd-am5-platform-b650-x670-x670e-chipsets-and-how-they-differ/ -- Grüße | Greetings | Qapla’ Please do not share anything from, with or about me on any social network. Greet every douche, for he may be your superior tomorrow.
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