I have a system with 4x 1080 Ti GPUs that were purchased three weeks ago for the purpose of password cracking. $3200 + shipping sold. Local pickup if you're around Atlanta. Here is a previous thread where I sold $8000 worth of hardware.

If you are going to reinstall the OS, take note that the motherboard does have a quirk where using 4 GPUs causes a resource conflict. Disabling a few resources in device manager will permanently fix the issue, but will also disable the audio and 2 usb ports (4 remaining will work). I have a screenshot marking which devices to disable.

• 4x GeForce GTX 1080 TI 11GB GDDR5X Founders Edition
• Corsair AX1500i (1500 Watts)
• ASUS ROG LGA1151 Z170 E-ATX MAXIMUS VIII EXTREME
• Intel Core i5 6500 3.20 GHz Quad Core Skylake
• 8 GB Ram
• 320GB HDD with Windows 10 64-bit

All components will be shipped with the original box they came in (the CPU and RAM will stay attached to the motherboard)