I have a asrock970 Extreme3 R2.0 that im looking to use a a mining rig it says 2 x PCI Express 2.0 x16 slots (PCIE2 @ x16 mode; PCIE4 @ x4 mode)
- 2 x PCI Express 2.0 x1 slots
- 2 x PCI slots
- Supports AMD Quad CrossFireX™ and CrossFireX™

Right i have 2 ATI AMD Radeon HD 7800 Series (XFX Pine Group) looking to add 3 or 4 more on this motherboard.

HOW MANY GPUS can I USE ON THIS MOTHERBOARD?

this is what i have that im looking to make a miner out of and add GPUS

Operating System
   Windows 10 Pro 64-bit
CPU
   AMD Phenom II X6 1050T   29 °C
   Thuban 45nm Technology
RAM
   8.00GB Dual-Channel DDR3 @ 665MHz (9-9-9-24)
Motherboard
   ASRock 970 Extreme3 R2.0 (CPUSocket)   31 °C
Graphics
   Acer G215HV (1920x1080@60Hz)
   1024MB ATI AMD Radeon HD 7800 Series (XFX Pine Group)   64 °C
   1024MB ATI AMD Radeon HD 7800 Series (XFX Pine Group)   75 °C
   CrossFire Disabled
Storage
   931GB Hitachi HDS721010CLA332 ATA Device (SATA)   27 °C
Optical Drives
   ATAPI iHOS104 ATA Device
Audio
   AMD High Definition Audio Device

THANKS