There is no such thing as a bad product, just bad pricing

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Let's assume that indeed Vega is a worst-case-scenario, and it's performance will fall short of what it's spec suggested. If so, I would say this should be the line-up:
- $600 = Fully unlocked and water-cooled Vega. This would be the 1080 Ti competitor (still a little weaker) that trades efficiency for more features and future proofing.
- In general this is just for the AMD fanboys.
- Even if it uses 400w, I think it is imperative AMD has something comparable to the 1080 Ti so that CPU benchmarks sometimes use an AMD card.
- Over time this will likely catch up to the 1080 Ti or higher, but it will take many driver revisions.
- $450 = Fully unlocked (or not?), lower clocked air-cooled Vega. This would narrowly beat the 1080 (Or trade blows) while using 250 - 300w.
- This is the card AMD needs to nail perfectly. Most people don't buy uber graphics cards, and something at this caliber is sorely needed at a lower price point.
- Paired with a Freesync monitor this would be a very attractive alternative to Nvidia's high-end cards.
- The fact that you could crossfire 3 of these for around the same price as a Titan Xp would be a big selling point.
- $350= Cut down, lower clocked, 4GB Vega. This is the card that beats the 1070 for a tad less money.
- A very important gap to fill between the RX 580 and RX Vega cards.
- I would expect 8GB and Nano variants.
- It would be sweet if they could make a GDDR5 version to further reduce price, but I know that won't happen.
^^^I know this is a long-shot, but I feel this is what's required to even have a chance of competing. Nvidia can surely drop prices by $50 across their entire line-up, and a minor Pascal refresh could be out by December (Or a 12nm refresh by Spring 2018). Plus even at these aggressive prices AMD would still be profiting some on each card.