Now would the system need to be aware of the 2 PCIe slot or will it magically work? probably when a second card is detected the selection port goes high on the chips and switches 16 pairs of to the other slot. So the ASM1480 is purely used to switch 16 of the 32 pairs to the other slot. and for 8x you still have 16 pairs total. EDIT: I figured it out You have a RX and TX Pair, so there are actualy 32 pairs total. So why use 4 ASM1480, capable of 16x multiplexing if you are running both slots at 8x/8x? Hmm I've looked this one up, MASSIVE IMAGE: You can see how the second red and fourth red slot are wired only for 8x, but here they have 8 times the ASM1480, but I guess they have the 4 needed for the bottom slot there as well, must have been easier to route. But they have 4 ASM1480 on the board between them. It only has the pins inside it to support 8 lanes. However, the second Red PCIe slot is physical 16x and signal 8x. If you take a really good look at the first picture at the top, the top PCIe slot is physical 16x and signal 16x. I hope you can assist me in figuring out what can actually be done in terms of splitting PCIe lanes. I've already found this PCIe Riser card which doesn't really seem to have any special components It mentions on the PCB that Slot 3 is PCIe 4x, so it actual splits the incoming 16 lanes into 8/4/4 I guess But this one has a lot of components but why does it have some many components? it even has a chip that needs cooling(might be a PLX chip), PLX allow for 16X input and 2x 16X output, magic. Now if this is true and I want to build a PCB that has 2 slots that are 8x do I actually need these chips? Couldn't I just route the first 8 lanes to the first slot and the back 8 lanes to the second slot? I will always have 2 cards installed so I wouldn't need to "optimize" bandwidth allocation. If a second card is inserted 2 of the cips are switched to send a total of 8 PCIe lanes to the second slot, giving each card half the bandwidth.
PCIE 3.0 SWITCH FULL
So if 1 card is inserted all chips are switched to send the PCIe lanes to the first slot, giving is the full 16x bandwidth. If I understand correctly they use ASMedia ASM1480 switches to switch 4 lanes per chip. It is done by motherboard manufactures for a while already.
So what I want to do is: build a PCB that switches a PCIe 3.0 16x lane into 2x slots that are PCIe 3.0 8x. The other problem is, I have ideas that I shouldn't really be trying with my current knowledge. Unfortunately I've gathered enough knowledge to be feared by most of the electronics around me, but I still have a long way to go. Hi everyone, New to the forum, but I've been watching EEVblog videos for a while now.
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