How many GPUs can I run on a Tiachi X299 Motherboard & i7 7740X CPU?


Oct 20, 2017
First of all YES! I know I shouldn't have bought the i7 7740X CPU!!!!! I was short on money and figured I would upgrade later. Which I still plan to do. But yes. It was a big mistake!

But for the moment I have 2 GPUs installed and an M.2 Drive. My usage is showing my primary GPU at x8, the secondary GPU at x4 and of course my M.2 Drive is using 4 PCI lanes.

I want to know if I can add an extra one or two more GPUs. I've gotten interested in mining crypto and just want to know if it's possible with the current 7740X. If I add a third GPU will my first one drop to x4? and I would have all 3 GPUs at x4? And if I added a 4th one would the M.2 Drive switch to using PCI lanes off the x299 chip set?

I have the manual for my Tiachi X299. The actual SKU information off Newegg is: ASRock X299 Taichi LGA 2066 Intel X299 SATA 6Gb/s USB 3.1 ATX Intel Motherboard

But I am having difficulting finding information about my question.

Thank you so much in advance to anyone who can help me understand these PCIe lanes.

I'd love to just drop an 8-core or 12-core CPU into it right now!

- 4 x PCI Express 3.0 x16 Slots*
- 1 x PCI Express 2.0 x1 Slot
- Supports AMD Quad CrossFireX™, 3-Way CrossFireX™ and CrossFireX™**
- Supports NVIDIA® Quad SLI™, 3-Way SLI™ and SLI™***

*If you install CPU with 44 lanes, PCIE1/PCIE2/PCIE3/PCIE5 will run at x16/x8/x16/x0 or x8/x8/x16/x8.
If you install CPU with 28 lanes, PCIE1/PCIE2/PCIE3/PCIE5 will run at x16/x0/x8/x0 or x8/x0/x8/x8.
If you install CPU with 16 lanes, PCIE1/PCIE2/PCIE3/PCIE5 will run at x16/x0/x0/x0 or x8/x0/x4/x0.

4 is the max, so can handle 2 more


Oct 20, 2017
Wait a minute. So the motherboard will handle 2 more. But when it says "x8/x0/x4/x0" does that mean all 4 slots will run? Is x0 valid? Or does that mean I can't run anything in the ZERO slots?

This is the part I struggle with to understand...

So if I upgrade to a 28 Lane CPU it still looks like it would only support 3 GPUs??? Unless the x0 is a valid variable?

I think maybe you looked at the Tiachi OC Formula board. I'm not being critical because I'll be the first to admit I'm way in over my head.

But when I clicked on the board in my items ordered list in Newegg it took me to the item screen and it shows these bullet points for the Tiachi X299.

X299 Taichi

ASRock Super Alloy
Supports Intel® Core™ X-Series Processor Family for the LGA 2066 Socket
13 Power Phase Design, Dr. MOS
Supports DDR4 4400+(OC)
4 PCIe 3.0 x16, 1 PCIe 2.0 x1
NVIDIA® 3-Way SLI™, AMD 3-Way CrossFireX™
7.1 CH HD Audio (Realtek ALC1220 Audio Codec), Supports Purity Sound™ 4 & DTS Connect
10 SATA3, 3 Ultra M.2 (PCIe Gen3 x4 & SATA3)
2 USB 3.1 10Gb/s (1 Type-A + 1 Type-C)
8 USB 3.0 (4 Front, 4 Rear)
Dual Intel® Gigabit LAN
Intel® 802.11ac WiFi
BIOS Flashback
Hyper BCLK Engine III

But even if it only supports 3-Way SLI it shouldn't mean I can't put 4 GPUs in the slots as long as I have enough lanes? Right? It's just I'm struggling to understand how many GPUs I can run with the limited numbe of lanes the i7-7740X offers (16 PCI lanes).

Can I run 4 at 4x each? or because of the x0 terms in the list you gave can I only run 2 at x8 and x4 respectively with the 16 lanes available?

I appreciate anyone that can shed light on this. :)


It should be able to divide it 4/4/4/4 but I won't say 100% that I know it can. It's just what I know of pcie lanes and how other miners have been putting more gpus on their mobos. Usually with x1 risers though.