Double true... But for me a steambox will always be Windows based PC running Steam big picture. Other platforms do not play a lot of the games. 

I currently have a Sapphire R9 290 Vapor-X in my system. It's a great card considering that the vapor-x line is the highest tier of R9 cards released. It barely breaks 70C under load, 75C under load when overclocked, and performs at about the same level as a reference 290X. Still, a 970 is a better solution in my eyes as it does run slightly better, and doesn't require a higher PSU. Also, it just seems as if the Maxwell series is more optimized for more games. There are several prominent games which the R9 series just doesn't seem to perform well under, likely because the games were designed with Nvidia's archetecture.

As far as a steambox, if you're buying the official steamboxes like the Alienware Alpha, you're already making a huge mistake because of the inability to upgrade the gpu. What a collossal waste of money. I'm with you. Get a copy of windows 7 off ebay for $65, run steam through big picture and you're done.

That's not because of the hardware but the software, and I'm not even talking about AMD's drivers here but the developers (specially Ubisoft) who have adopted Nvidia's GameWorks that, despite what they said, does hinder the performance of the games that use it on non Nvidia GPUs.

sorry to step in but the highest tier is from ASUS with thier ROG Matrix cards.

Both Nvidia & AMD(ATI) are fine cards but the problem is the developers... Because most of them using heavily modified engines, yes a heavily modified engines, this is how they made unoptimized games too carelessly.

I'd rather not to buy serious gaming PC until 3 major games come out. Half-Life 3, Unreal Tournament 4 & Doom(aka Doom 4)

Do you just mean in price? Because certainly not in performance.

im not going by price, the ROG cards have several features not found on the sapphire cards not to meantion unlocked voltage which is also on the XFX cards, just because the sapphire cards have 3 fan's does not mean they perform better!

It's not just because it has more fans, it's because Sapphire is dedicated to AMD cards. ASUS isn't. It's the same reason EVGA makes the best Nvidia cards. It's because they're exclusive to Nvidia. The ROG Matrix is recycling the DirectCU II cooler that's on the GTX 700 series cards, so it isn't even designed to combat the R9's ridiculous heat output. 

But don't take my word for it. Dare to compare.

http://www.hardocp.com/article/2014/09/08/asus_rog_r9_290x_matrix_platinum_video_card_review/1#.VJpdrUAAA

http://www.hardocp.com/article/2014/08/01/sapphire_vaporx_r9_290x_trix_oc_video_card_review/1#.VJpdoUAAA

The Vapor-X at base runs around as well as the ROG Matrix does Overclocked, and the ROG Matrix hits the thermal limit that AMD has on R9 cards which is 94C with 100% fan speed. The Vapor-X reaches 72C with 100% fan speed. Overclocked, the Vapor-X wins in every game except for Farcry 3, perhaps. Seems pretty clear to me. Unless you want ridiculous features like Liquid Nitrogen compatibility, (which is kind of pointless, as anyone who is planning on running a rig for that is going to be buying 780 ti's because they're faster) the Vapor-X is the clear winner. It not only manages to perform better in games, but it does so much cooler.

EDIT: And they're both priced at around $630 without discounts, so they're the same tier on pricing.

the fact is that while you can go on about this that and the other getting away from the actual point, just because the Sapphire card performs better under air cooling does not instantly make it the top tier card, the way your saing it is like saying AMD's reference design for the 295X2 is better than ASUS's ARES III card, not that sapphire though dedicated to AMD have not made their own dual GPU card that runs as cool as the ASUS card, Sapphire are good for value vs performance while ASUS's ROG is all about performance, the Matrix card has LN2 and a molex connector to heat up the vram while the card is running record breaking overclocks, something the varpor X does not have.

EVGA may be Nvidia only but that doesn't stop ASUS from producing some ground breaking cards their either, a perfect example is their MARS III card ( a dual 760 on one PCB) even Nvidia hadn't made a dual 760 and neither had EVGA, don't just fall for the assumption a manufacturer dedicated to one companie is better than one that caters for many.

I thought about writing up a long, detailed response to your points, but figured there's no point. The fact of the matter is that the cooler on the ROG Matrix is fundamentally not suitable for cooling the R9 290x's Hawaii GPU. I don't know why you brought up other cards which are not at all analogous to the ones we're talking about, or watercooling for custom PCB cards which are not geared towards watercooling because you have to take off the cooler, so you're paying a premium for just about no reason, but none of that is relevant. I've given you evidence which shows that despite all of the superfluous features the ROG Matrix has, it still cannot perform as well as the Vapor-X when both are overclocked to its limit. in most cases, it performs about as well overclocked as the Vapor-X does at stock levels. They're both the same price as well. The Vapor-X is the highest tier of aftermarket R9 cards you can buy.

As far as EVGA being superior because it is Nvidia only, there are multiple reasons for why they make the best Nvidia cards, but it doesn't seem to matter if I tell you them because you'll just assume I'm blindly supporting the company because they're exclusive to Nvidia.

And with that, I'm bowing out. There's no point in getting hostile over something that is really irrelevant at this point, because premium 290x's are becoming obsolete.