Not the first time either, this round a batch of Gigabyte gra[phicss cards was listed,. and along the naming comes the value of graphics memory. Which will be become 8GB for the Radeon RX 6600 XT. A new update can be made though.

As you'll notice, Gigabyte added six Radeon RX 6600 XT graphics card models to EEC:

• Gigabyte Radeon RX 6600 XT Gaming OC PRO (GV-R66XTGAMINGOC PRO-8GD)
• Gigabyte Radeon RX 6600 XT Gaming PRO (GV-R66XTGAMING PRO-8GD)
• Gigabyte Radeon RX 6600 XT Gaming (GV-R66XTGAMING-8GD)
• Gigabyte Radeon RX 6600 XT Gaming OC (GV-R66XTGAMING OC-8GD)
• Gigabyte Radeon RX 6600 XT Eagle OC (GV-R66XTEAGLE OC-8GD)
• Gigabyte Radeon RX 6600 XT Eagle (GV-R66XTEAGLE-8GD)

And they all are listed to get 8GB GDDR6. ASRock back in may had a listing that matches that 8GB, so that's a certainty at this point. Radeon RX 6600 XT will be based on Navi 23 XT for its GPU. You should expect high clock frequencies (up to 2.9 GHz is even mentioned) with relatively low power consumption in the 100W range. Below the preliminary specs as tabled by videocardz, remember that this is intended to be a Full HD domain card.

Update: new entries have been found in drivers as well, the 6600 XT and 6600 seem close to an official announcement. Driver support is there, and board partners are ramping up their designs. Twitterer Komachi_Ensaka noticed the cards carry PCI-device ID 73FF. This ID number corresponds to the Navi 23 GPU already used by the mobile Radeon RX 6600M. In short, So the desktop GPUs are equipped with a Navi 23 GPU. 

AMD Radeon RX 6600 XT with 8GB now also pops up in driver entries (updated)