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ROGBot
I've got an X570 Crosshair VIII Hero. I just switched my M.2 drive in the first M.2 slot (under the video card) and I ran into the same issue that confused me when I first put the system together. In that slot, the Asus-provided heatsink/cover screws into an offset that doubles as the place where a screw is supposed to hold down the M.2 drive:
Well, my original photo was oriented better. Anyway you can see the two (empty) intermediate standoff spots and then the one that's got the standoff in it. Because the Asus-provided heatsink/cover uses that standoff, I can't screw the M.2 drive down before attaching the sticky Asus-provided heatsink/cover. So, I have to hold it down with my finger while I attempt to screw the adhesive-attached Asus-provided heatsink/cover down on top of it. Either that or go without the Asus-provided heatsink. Am I doing something wrong here?
Now, the second M.2 slot (at the bottom of the motherboard):
is longer and doesn't have that issue. You can see three intermediate standoff positions and then the one used to screw down the Asus-provided heatsink/cover (I've put the Asus-provided standoff/screw into the 3rd intermediate position to show where that would go for a "normal" (2280) M.2 (and so I don't lose it)). Since the motherboard is an X570 and I'm using a Ryzen 3700X, both of those M.2 positions should be running at the same PCI4 speed. Except when I measured it with the default Crystal DiskMark M.2 tests, the 2nd position was roughly 15% slower than the 1st position.
First M.2 slot:
and second M.2 slot:
EDIT: When I ran the test on the first M.2 position, I watched the temperatures of the drive in HWINFO64. According to that, the controller temperature (Drive Temperature 2) never budged from 71 degrees C (I've never seen it budge at all -- it's the same temperature even immediately after a cold boot). The drive's memory temperature (Drive Temperature 1) increased by 21 degrees C during the test: from a stone-cold, cold-boot temperature of 28 degrees C to 49 degress C at its peak. Right now, it's idling at 31 degrees C. So, the Asus-provided heatsink/cover (along with the graphene heat spreader/label on the M.2 drive, itself), seems to be working fine. I just don't know if there's a better way to install it.
Well, my original photo was oriented better. Anyway you can see the two (empty) intermediate standoff spots and then the one that's got the standoff in it. Because the Asus-provided heatsink/cover uses that standoff, I can't screw the M.2 drive down before attaching the sticky Asus-provided heatsink/cover. So, I have to hold it down with my finger while I attempt to screw the adhesive-attached Asus-provided heatsink/cover down on top of it. Either that or go without the Asus-provided heatsink. Am I doing something wrong here?
Now, the second M.2 slot (at the bottom of the motherboard):
is longer and doesn't have that issue. You can see three intermediate standoff positions and then the one used to screw down the Asus-provided heatsink/cover (I've put the Asus-provided standoff/screw into the 3rd intermediate position to show where that would go for a "normal" (2280) M.2 (and so I don't lose it)). Since the motherboard is an X570 and I'm using a Ryzen 3700X, both of those M.2 positions should be running at the same PCI4 speed. Except when I measured it with the default Crystal DiskMark M.2 tests, the 2nd position was roughly 15% slower than the 1st position.
First M.2 slot:
and second M.2 slot:
EDIT: When I ran the test on the first M.2 position, I watched the temperatures of the drive in HWINFO64. According to that, the controller temperature (Drive Temperature 2) never budged from 71 degrees C (I've never seen it budge at all -- it's the same temperature even immediately after a cold boot). The drive's memory temperature (Drive Temperature 1) increased by 21 degrees C during the test: from a stone-cold, cold-boot temperature of 28 degrees C to 49 degress C at its peak. Right now, it's idling at 31 degrees C. So, the Asus-provided heatsink/cover (along with the graphene heat spreader/label on the M.2 drive, itself), seems to be working fine. I just don't know if there's a better way to install it.
After looking over the manual some more, I guess I have some theoretical answers to some of the questions in this thread. First, as to installing a 2280 M.2 in the first slot, I guess I'm doing it "correctly." Here's a zoomed in picture from the manual:
Since M.2 drive's don't naturally lie flat in their sockets, I guess I'm supposed to use one hand to hold the M.2 down, another hand to position the adhesive coated cover/heatsink onto it, another to use a screwdriver on the teeny-tiny screws. And throw a couple more hands in there just because it's persnickety.
Regarding the speed, both M.2 sockets can run at PCIe 4.0 x 4 speed, though the first socket is handled by the CPU and the second socket is handled by the chipset. Since this is an X570 chipset, both sockets will run at PCIe 4.0 speed. The Storage blurb in the manual:
and the Operating Mode blurb:
But, the problem is the x4 lane between the chipset and the cpu:
Right there in the middle of the diagram. So, yes, the second M.2 slot has x4 lanes dedicated from it to the chipset. But, anything it needs the CPU to do has to compete with whatever else wants to go across the x4 lane between the chipset and the cpu. Probably not a lot of traffic, but probably some effect. Also, that communication would have to go through 2 hops instead of the 1 one from the first M.2 slot.
As for my thinking about a multi-M.2 PCIe 4.0 expansion card, here's the manual's blurb about expansion slots:
Unless I limited my GPU to x8 mode, the 2nd PCIe slot is useless. That would put me into the 3rd PCIe x16 slot which is electrically x4 (which is fine for an M.2). But, it would be connected to the chipset, just like the 2nd M.2 socket on the motherboard. Plus, at x4, it could only hold one M.2 drive. So, there's no point in that.
Oh, well. Not happy answers. But, interesting ones.
Since M.2 drive's don't naturally lie flat in their sockets, I guess I'm supposed to use one hand to hold the M.2 down, another hand to position the adhesive coated cover/heatsink onto it, another to use a screwdriver on the teeny-tiny screws. And throw a couple more hands in there just because it's persnickety.
Regarding the speed, both M.2 sockets can run at PCIe 4.0 x 4 speed, though the first socket is handled by the CPU and the second socket is handled by the chipset. Since this is an X570 chipset, both sockets will run at PCIe 4.0 speed. The Storage blurb in the manual:
and the Operating Mode blurb:
But, the problem is the x4 lane between the chipset and the cpu:
Right there in the middle of the diagram. So, yes, the second M.2 slot has x4 lanes dedicated from it to the chipset. But, anything it needs the CPU to do has to compete with whatever else wants to go across the x4 lane between the chipset and the cpu. Probably not a lot of traffic, but probably some effect. Also, that communication would have to go through 2 hops instead of the 1 one from the first M.2 slot.
As for my thinking about a multi-M.2 PCIe 4.0 expansion card, here's the manual's blurb about expansion slots:
Unless I limited my GPU to x8 mode, the 2nd PCIe slot is useless. That would put me into the 3rd PCIe x16 slot which is electrically x4 (which is fine for an M.2). But, it would be connected to the chipset, just like the 2nd M.2 socket on the motherboard. Plus, at x4, it could only hold one M.2 drive. So, there's no point in that.
Oh, well. Not happy answers. But, interesting ones.
