Max XII Extreme - Does the Thunderbolt take PCIe lanes

[martine-dee]

Hi,

I come here with a MAX XII question. I realize those are Max X/XI forums, but I haven't found a better match for Max XII atm. :/

So, I am new to Maximus, and new to Thunderbolt. In reviews, I saw that the Max XII Extreme comes with a Thunderbolt 3 card. Well, cute, I never used it, probably never will have the need, but since it is there and boosts up the price tag so much, I wonder how it would work.

Particularly, I would like to keep the x16 for the card, and the PCIe pins on Thunderbolt card look to me like using it would mean the x8/x8 mobo mode. [ The manual ] is not explicit about this, thus it is probably generally known.

So... is there a way to utilize this included Thunderbolt 3 card while keeping the video card at x16?

Thanks!

[Jesseinsf]

It uses the Z370/Z390/Z490 chipset, so it will not affect your graphics card at all. Here is the issue though. The Z370/Z390/Z490 chipset does have 24 PCIe internal lanes. But it can only communicate and send data to and from the CPU/Memory at PCIe 4X speeds. If you have a Samsung 970 pro and a Thunderbolt card then you are already bottlenecking the heck out of the chipset's bandwidth to the CPU/Memory (especially if you are connecting a display to the Thunderbolt card). This will negatively affect all other data peripherals like WiFi, LAN, Sata drives and many things connected to the USB ports

A note from the Specifications page:

*1 PCIEx4 slot shares bandwidth with SATA6G_56 and PCIEx4 slot is default set at x2 mode. Please adjust BIOS settings to enable Thunderbolt card.

[martine-dee]

Thanks! I've caught up a bit later with the Z490 architecture.

A cool thing about this x4 slot is that I can use it for my AE-9, which only needs one PCIe lane. Then the graphics card can remain at x16.

Plugging the M.2 SSDs via DIMM.2 will set the graphics card to x8 from what I've seen.

[btrach144]

Thanks! I've caught up a bit later with the Z490 architecture.

A cool thing about this x4 slot is that I can use it for my AE-9, which only needs one PCIe lane. Then the graphics card can remain at x16.

Plugging the M.2 SSDs via DIMM.2 will set the graphics card to x8 from what I've seen.

Yep, that's right. I use the motherboard slots for my 970 Pro RAID 0. The DIMM card is a cool idea but I hate that it drops my 2080Ti to x8.

I know most people say x8 won't bottleneck a 2080Ti by more than 5% but I'm gaming at 4K 144Hz and need every FPS that I can get.

[martine-dee]

Yeah, i resisted for long going down the Maximus lane, out of scare that it only has x16 for the graphics card and that's it. It is serendipitous that AE-9 can work without affecting the x16 for the graphics card. Also, it is great that I didn't order any M.2 drives for this PC. SATA SSDs will have to make due.

[Jesseinsf]

Yeah, i resisted for long going down the Maximus lane, out of scare that it only has x16 for the graphics card and that's it. It is serendipitous that AE-9 can work without affecting the x16 for the graphics card. Also, it is great that I didn't order any M.2 drives for this PC. SATA SSDs will have to make due.

Just remember the Chipset can handle up to 24 lanes, but can only output 4 lanes to the CPU/Memory. The 4X slots uses the Chipset, so does everything you plug in to the USB, LAN, Wi-Fi, the 3rd PCIe X16 slot. This means that it is easy to cause a bottleneck in performance through the chipset (Excluding the graphics card and DIMM.2). Graphics card and DIMM.2 are on a separate direct 16X link to the processor and memory.