Sorry for multiple posts! Asrock 870E PCIE Confusion

Hardware Hub Motherboards
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Please help clarify the specs for the 870E Taichi PCIE 5.0 slot specs. In your video “Finally a board without RGB!…” you state the 2 PCIE 5.0 slots operate with PCIE1 at x16 or PCIE1 and PCEI2 at x8/x8. The specs in the actual manual state (please note the asterisk)…
Expansion Slot CPU: • 2 x PCIe 5.0 x16 Slots (PCIE1 and PCIE2), support x16 or x8/ x8 modes*

  • PCIE1 and PCIE2 will run at Gen5x16 with 9000 and 7000 series processors, Gen4x8 with 8000 (Phoenix 1) series processors and Gen4x4 with 8000 (Phoenix 2) series processors.
    If the Asrock manual is accurate, they are the only manufacturer stating both PCIE 5.0 slots will run at x16 with a 9000 or 7000 series cpu.
    Can you please help clarify this? How can Asrock achieve this when Asus, MSI, Gigabyte all spec their two PCIE slots at x16/x8 or x8/x8 if both slots are used?
    Asrock also states crossfire is supported (in 2024)?
    Asrock is also the only 870E manufacturer that doesn’t disable M.2 slots (or downgrade to x2)if PCIE1 and various combinations of M.2 slots are used.
    As an avid PC flight simmer, the Asrock looks like a dream board, but as the only manufacturer with these specs, I’m Leary that they are accurate.
    Please help clarify?
    Many thanks
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welndell accuracy 1
ASRock 0

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Not sure what you’re asking about but motherboards without RGB are nothing new.
ASUS ProArt-series for example (if you’re looking at the higher end) and they offer what you’re asking about too (your post is a bit confusing). I honestly don’t see why you’d go for the Taichi over ProArt in general though especially since it uses Intel NIC over Realtek although “only 2.5G”. That being said, since the PCIe configuration is a bit different than X670E you might want consider such a motherboard instead depending on your requirements.

Just to be clear, it’s 8x 8x not 16x 16x on these boards

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I took a loot into the Taichi Lite manual. The slots either run x16/x0 or x8/x8. Depending on CPU/APU the lane count and generation will change.

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This is not what the Taichi manuals say. The OP image is broken and the formatting mangled but what’s quoted is the fine print on the X870E Taichi Lite and Taichi product pages. It could be worded better but, no, ASRock does not somehow increase the Zen 4 and Zen 5 desktop IO die from 28 PCIe lanes to 36 or 44. As @MazeFrame mentioned, refer to the block diagrams in the manuals to see how the 16 PEG lanes are switched from x16/x0 to x8/x8 bifurcation.

Crossfire, I dunno.

I think there’s confusion about how x16 bifurcation works and perhaps some lack of accounting for M.2s and USB 4 on the desktop IO die’s other eight lanes. All X870E boards offer the choice to use all 16 PEG lanes for a dGPU (that I’m aware of, but maybe there’s a weird one). Tabling out boards’ PCIe lane configurations in your build spreadsheet by expanding the below to include chipset lanes may be helpful.

mobo PEG CPU M.2 CPU USB 4
Asus Crosshair X870E x16, x8/x8, x8/M.2/M.2 5.0 x4 very likely ASM4242
Asus ProArt X870E Creator x16, x8/x8, x8/x4/M.2 5.0 x4 very likely ASM4242
Asus Strix X870E-E Gaming x16 5.0 x4 probably ASM424
ASRock X870E Taichi x16, x8/x8 5.0 x4 ASM4242
ASRock X870E Taichi Lite x16, x8/x8 5.0 x4 ASM4242
ASRock X870E Nova x16 5.0 x4 ASM4242
Gigabyte X870E Aorus Master x16, x8/M.2/M.2 5.0 x4 ASM4242
Gigabyte X870E Aorus Elite x16, x8/M.2/M.2 5.0 x4 ASM4242
Gigabyte X870E Aorus Pro (Ice) x16, x8/M.2/M.2 5.0 x4 ASM4242
MSI X870E Godlike x16, x8/x8 5.0 x4 probably ASM4242
MSI X870E Carbon x16, x8/x4/M.2 5.0 x4 very likely ASM4242

Bifurcating x16 to x8/x8 is for dual GPU as seems to have been noted. x8/x4/x4’s usually to add two M.2s, though the Carbon brings out one x4 to a slot instead. Gigabyte, like ASRock, does block diagrams. So their manuals may also be helpful here. Asus and MSI don’t show their lane allocations, at least in the manuals I’ve checked.

Because they’re the only one of the big four not to offer an X870E board with x8/x4/x4 bifurcation.

Also, once the chipsets are tabled in to be able to fully compare boards on an M.2 basis, I’m pretty sure what you’ll find is the x2s are chipset lane reallocations. In particular, it’s common to bifurcate a Promontory 21’s 3.0 x4 port from x4 NVMe to x2 NVMe/x1 SATA/x1 SATA.

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If you need two slots, you will want the Asrock Nova as the PCIE 1 is 5.0 x16 and the PCIE 2 is 5.0 x2.

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Its pretty sad things have gone backwards.

I asked ChatGPT if there are any 870 boards that support my requirement of a GPU at x16 + 2 gen 5.0 m.2 drives WITHOUT my GPU being reduced to x8.

After a bit of prompting it suggested there were none and that I should look at an X670E instead!

Seems crazy even with the overall lane limitations this isn’t an option from someone, I don’t want 15 USB sockets, USB4, audio (I have a soundbar) or hell even a 2nd PCIE slot, I just want 2 large PCI5.0 drives and my x16 GPU ready for a 5090 or 6090 in a few years.

Instead they will try and rinse me again to upgrade to AM6

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ChatGPT is not the sharpest knife in the drawer

  • the MSI X890 Tomahawk has the option to disable the USB4 controller (the ASM4242 chip uses 4 lanes from de cpu directly) and use the freed up 4 PCIe 5.0 lanes for a 2nd nvme. So you can have 16 PCIe 5.0 lanes dedicated for the gpu and 8 PCIe 5.0 lanes dedicated for two nvme drives. The remaining 4 lanes are used for the chipset connection.
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So you either go x670e with no USB4 or you go x870 (no e). Pretty much any board that has USB4 is going to leave you starved for PCie 5 lanes. The x870 Tamahawk is one of the few that allow to disable the USB4 to give the lanes to m.2. I know that you have certain requirements but with enough PCIe 4 m.2 slots, why is 2 PCIe 5 m.2 slots a hard requirement?

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