Of course there is nothing stopping it. But it drives up cost to add PCI-E switches and it still isn't ideal. Just outright having more PCI-E lanes available from the beginning is the better solution.
Implementing switchable PCIe through the chipset is free, as the functionality is built in. The only thing driving up costs would be adding the required lanes and ports, which you're asking for more of, not less.
The number of GPUs has nothing to do with the discussion. The GPU gets it's lanes from the CPU, not the chipset. These downstream lanes off the chipset are what I'm talking about and there are already boards that are running out of them.
But PCIe lanes are PCIe lanes. If you need more than the 16 off the chipset, use the second x16 slot from the CPU. Your GPU will lose maybe 1% of performance at worst, and you'll get 8 more PCIe lanes to play around with. And again, if that 1% of performance is so important to you, buy an HEDT platform.
As for a 25w TDP, no that also is unreasonable and if it was that high then that is also a fault of AMD. The Z390 gives 24 downstream lanes and has a TDP of 6w, and it's also providing more I/O than the X570 would be. The fact is, thanks to AMD's better SoC style platform and the CPU doing a lot of the I/O that Intel still has to rely on the southbridge to handle, the X570 has a major advantage when it comes to TDP thanks to needing to do less work. And I'd also guess the high 15w TDP estimates of the X570 come down to the fact that they are using PCI-E 4.0.
Yes, the TDP is obviously due to PCIe 4.0 - higher frequencies means more power. That's a given. And 15W is perfectly fine (especially as it's only likely to pull that much power under heavy loads, which will be infrequent), but 25W would be problematic as you won't be able to cool that well passively without interfering with long AICs.
So, again, at this point in time I would rather them put more PCI-E 3.0 lanes in and not bother with PCI-E 4.0 in the consumer chipset. The more lanes will allow better motherboard designs without the need for switching and port disabling. It would likely lower the TDP as well.
Well, tough luck I guess. I'm more interested in a more future-proof platform, and I'm reasonably sure that I'll be more than happy with 16+16 PCIe 4.0 lanes. I'm more interested in the push for adoption of a newer, faster standard (which will inevitably lead to cheaper storage at 3.0 x4 speeds once the "new standard" premium wears off and 2-channel 4.0 controllers proliferate) than I am in stuffing dozens of devices into my PC.
And of course, yes, more 3.0 lanes would allow for more ports/slots/devices without the need for switching, and likely lower the TDP of the chipset. But it would also drive up motherboard costs as implementing all of those PCIe lanes will require more complex PCBs. The solution, as with cheaper Z3xx boards, will likely be that a lot of those lanes are left unused.
And the mainstream users are likely not using X570 either. They are likely going for the B series boards, so likely B550. They buy less expensive boards, with less extra features, that require less PCI-E lanes. But enthusiasts that buy X570 boards, expect those boards to be loaded with extra features, and most of those extras run off PCI-E lanes.
That's not quite true. Of course, it's possible that X570 will demand more of a premium than X470 or X370, and yes, there are
a lot of people using Bx50 boards, but the vast majority of people on X3/470 are still very solidly in the "mainstream" category, and have relatively few PCIe devices.
Phison isn't going to be selling drives to the consumer, they never have AFAIK. So it doesn't matter how well know they are to the consumer, they are very well known to the drive manufacturers. They sell the controllers to drive manufacturers, and the drive manufacturers sell the drives to consumers. Phison will charge more for their controller, and the drive manufactures will charge more for the end drives. They will charge more because the controller costs more, as well as the NAND to get actual higher rated speed costs more, and the have the marketing gimmick of PCI-E 4.0.
No, they won't but they will be selling them to OEMs. Which OEMs? Not Samsung - which has the premium NVMe market cornered - and not WD, which is the current NVMe price/perf king. So they're left with brands with less stellar reputations, which means they'll be less able to sell products at ultra-premium prices, no matter the performance. Sure, some will try with exorbitant MSRPs, but prices inevitably drop once products hit the market. It's obvious that some will use PCIe 4.0 as a sales gimmick (with likely only QD>32 sequential reads exceeding PCIe 3.0 x4 speeds, if that), but in a couple of years the NVMe market is likely to have begun a wholesale transition to 4.0 with no real added cost. If AMD didn't move to 4.0 now, that move would happen an equivalent time after whenever 4.0 became available - in other words, we'd have to wait for a
long time to get faster storage. The job of an interface is to provide plentiful performance for connected devices. PCIe 3.0 is reaching a point where it doesn't quite do that any more, so the move to 4.0 is sensible and timely. Again, it's obvious that there will be few devices available in the beginning, but every platform needs to start somewhere, and postponing the platform also means postponing everything else, which is a really bad plan.
Just put your 4x M.2. card in and an I/O card and you are rocking and still have 2 full x16 slots to pop the GPUs in as well as all the chipset stuff.
) slot. So plugging in an additional M.2 drive disables the PCI-E slot.