You might want to list all of your Hardware to allow others to help you.

What version of Windows 10 are you running?
Can you see the Graphics Card in your Motherboard Bios?
Is the Bios on your Motherboard up to date?
Is the On Board Video Card Disabled in the Motherboard Bios?
Is the Default Video set to PEG in the Bios or set to the PCIe?
 
AMD Ryzen 7 2700X 3.70 GHz 20MB AM4 12NM
Asus x470 Tuf Plus Gaming  AM4 ATX
https://www.asus.com/us/Motherboards/TUF-X470-PLUS-GAMING/
BIOS Version 4602 2019/03/26 10.26 MBytes DOWNLOAD 
Chipset Version 18.50.16.01 2019/04/03372.41 MBytes DOWNLOAD
EVGA GTX1070Ti SC Black Edition 8GB GDDR5 256Bit  DX12
https://www.evga.com/products/specs/gpu.aspx?pn=1B36599D-EEC9-4DE1-8F3A-80998ED252D7
Corsair 16GB(2x8) Vengeance Lpx Black 3000MHz CL16 DDR4
Sandisk 120GB SSD Plus
Sandisk 240GB SSD Plus
WD 1TB Blue 64MB 7200rpm
FPS Hydro 700W 80+ Bronze

Th3W4sp
I am using Windows 10 pro. I updated the motherboard a few minutes ago.
"Is the On Board Video Card Disabled in the Motherboard Bios?"
"Is the Default Video set to PEG in the Bios or set to the PCIe?"
I didn't find the BIOS settings you said. Where is it?

Can you see the Graphics Card in your Bios?
If so is it running at X8 or X16?
 
https://dlcdnets.asus.com/pub/ASUS/mb/SocketAM4/TUF_X470-PLUS-GAMING/E13882_TUF_X470-PLUS_GAMING_UM_WEB.pdf
Page 3-13
Primary Video Device Selects the primary display device.
Configuration options: [IGFX Video] or [PCIE Video]
Page 3-14

 
 

Th3W4sp
I don't know exactly where to look. I can't find the settings you said in the BIOS.
https://i.hizliresim.com/y6gy3M.jpg
https://i.hizliresim.com/nQZvWa.jpg

We Cannot see the Images.
Maybe pull the CMOS Battery from your Motherboard to Clear the CMOS.

Th3W4sp
I think the graphics card is faulty. 

Two in a Row, Not Normal.
Can you test the card in another computer?
Or just use it in the lower PCIe Slot.  "It works in the slower PCIE slot.:"
Most likely a Motherboard Issues and not a Graphics Card.
That Motherboard is meant to use an AMD Graphics Card in and not really a NVIDIA Card.
Supports AMD CrossFireX™ Technology (NO SLI SUPPORT)

I guess then you might need to do another RMA.

There are small AC decoupling capacitors on the video card right next to the PCI-E slot connection. They are pretty easy to knock off, are close enough to the slot to make it a risk in handling, and are small enough to be hard to notice if they are missing. When one/some get knocked off, one symptom is that the card won't work at certain PCI-E link widths/generations.

Take the card out and look closely at the front and back of the card for burnt, missing, discolored, or otherwise damaged capacitors near the PCI-E slot. Also look at the PCI-E slot "fingers"/contacts and electrical traces for discoloration, scratches, scrapes, or any other type of damage.

Example of a missing PCI-E decoupling capacitor:




Let us know. If you find damage, it may or may not be something covered by warranty; depending on whether you can prove that it came from EVGA in its present condition.


On the other hand, since you already replaced the motherboard, its not likely that the new motherboard is also faulty (unless you accidentally damaged the slot during installation), but it is possible that your CPU is faulty and that is why certain slots or PCI-E generations don't work any more. Not likely though. Physical damage to the video card (or motherboard slot) is much more likely.

its not working in the first slot because you turned on Hyper M2X16 support in the bios.
 
The  graphics card has absolutely no knowledge of what slot its in, there is no possible reason for it to not work in 16x_1 without user misconfiguration across 2 different mainboards.

Th3W4sp
What should I do?
The computer does not start at all on when I put the graphics card on the PCI 3.0x16 slot. I didn't find a setting for which slot to use in the BIOS.

 
Check page 3-14 in your manual...I know RTX and GTX cards work in this board, since I've built 2 ...one with a GTX1080 and one with an RTX 2070.
 
You need to check all the settings in your bios...and I would personally take the battery off the motherboard and leave it for about 5 minutes.....
 
 
 

Th3W4sp

Normal

I'd try the following...
 
#1 Clear the cmos using the on-board clear cmos jumper. See page 1-8 of the user manual for further details.
#2 Set the option "PCIEX16_1 Bandwidth" to x8 mode inside the bios. See page 3-14 of the user manual for more details.
 
Online user manual: https://dlcdnets.asus.com/pub/ASUS/mb/SocketAM4/TUF_X470-PLUS-GAMING/E13882_TUF_X470-PLUS_GAMING_UM_WEB.pdf

Yeah, the online manual explains why it isn't listed. Does your video card run at x8 speed in the second slot, or does it run at x4?

"#1 I've cleared CMOS with a metal object" is not the same as pulling the CMOS Battery for 15 Minutes.

Sajin
 
Thanks. Do you know if your card is running the same vbios as your older card?
 

 
I used my first graphics card in PCIE 3.0 x16 (x16) slot for 1 month. Then my graphics card failed and was replaced with the RMA product. The RMA product did not work in the PCIE 3.0 x16 slot on the Asus Tuf b450 motherboard. It works on PCIE 2.0 x16 (x4). I thought the motherboard might be break down and I updated it. I bought a new Asus X470 Tuf Plus Gaming motherboard. It didn't work. My graphics card was still not working on the PCIE 3.0 x16 slot.