The first RTX 4070s with slower GDDR6 memory are now available to buy but there isn't a single reason to do so at the moment
If you're looking to upgrade to a new RTX 4070 GPU, don't go for Asus' new model fit with GDDR6 VRAM. At least, not at its current price.
As pointed out by Tom's Hardware, the new GDDR6 model of the Asus Dual RTX 4070 is available to buy at Newegg for $570. An impressive card—it comes with 12 GB of GDDR6 RAM and has a core clock speed of 2,520 MHz, which can boost up to 2,555 MHz. Despite being less strong than the GDDR6X model, due to being a tad slower, it's more energy efficient and has entered production to ease supply issues.
However, it's worth noting that the GDDR6X loaded version of that card is the exact same price on Newegg, at the full price of $570. Given the former isn't even in stock right now and the latter is available to buy, I don't see any reason to pick the slightly downgraded card.
Even if the GDDR6X model goes out of stock, it's probably a slight upgrade worth waiting for, given you are paying the same amount. The slightly better card even comes with a digital copy of Star Wars Outlaws, which is perfect for testing that new upgrade with.
In practice, the 12 GB of GDDR6X RAM has a memory speed of 21 Gbps, whereas the GDDR6 version has a memory speed of 20 Gbps. This is so light a downgrade that it should only negatively impact memory bandwidth by a small margin. This is so little that if the new card had a very slight discount, it would probably be worth going for that instead. Right now, though, the current pricing is confusing at best.
That being said, the value proposition on modern graphics cards can be hard to navigate in the first place. Given Nvidia's RTX 4070 Super card, one of the best graphics cards right now retails at the same price as its 4070, the only reason one might go for the weaker card is if it sells for cheaper.
The same could be true here, where, as stock starts to filter out, the GDDR6X model sells for a fraction more. This isn't the only time a new card has been released that is massively outclassed by its older card. In 2021, an RTX 2060 12GB was spotted in the middle of a graphics card drought, significantly above what was expected. This made a little more sense as cryptocurrency miners hit their peak in popularity.
The 4070 is a super capable card but also the only one that really makes sense at the exact right time and for the exact right price. Otherwise, there's probably a better choice out there.