DPReview added the Canon EOS 5D Mark IV to their studio scene comparison tool. If you want to compare the Canon EOS 5D Mark IV image quality and ISO performance to other cameras then this tool can help.
Canon EOS 5D Mark IV world-wide pre-order links (please note: not all oversea retailers have the EOS 5D Mark IV already available)
Australia: Amazon, Adorama, B&H Photo, Digitalrev, eBay Australia, Alibaba
Canada: Amazon Canada, DigitalRev, Adorama, B&H Photo, eBay Canada, Canon Canada, KEH Camera
France: Amazon FR, DigitalRev, eBay FR, Canon France
Germany/Austria/Switzerland: Amazon DE, DigitalRev, eBay DE, Wex Photo Video, Canon Deutschland
United Kingdom/Ireland: Amazon UK, Park Cameras, Wex Photo Video, DigitalRev, eBay.uk, Canon UK
USA: Amazon, B&H Photo, Digitalrev, eBay, Adorama, KEH Camera, Canon USA