Yoplait95 :
Tom Tancredi :
If he went purely just 290 , each is 650W which would make 1300W needed, not to even consider ANY other 290 (CF, 290X, etc.)
http://www.realhardtechx.com/index_archivos/Page362.htm That isn't even considering all the cooling you would need to power on top of it (liquid pump, radiators, etc.) . THESE guys were DOING what the OP is asking for (4k Display) and used a 1350W and ran into problems right off when they went Dual GPU while it worked perfectly fine for OLDER QUAD GPUs http://www.hardocp.com/article/2014/04/29/amd_radeon_r9_295x2_crossfire_video_card_review/
So YEAH you need at LEAST 1600W PSU thank you very much
On your own link.. 1000 max.. Hes not going for the 295x2
Stop and read again, first link, R9 290 650W - OP said "2 R9 290'" that is 650w x 2 or 1300W. I dont' see what your talking about 1000W Max. Also look at point three below.
Second Link " as well as a single GPU AMD Radeon R9 290X. We are using an XFX R9 290X DD as our single-GPU card at 4K and Eyefinity because it does not throttle performance." Using a "R9 290" would throttle performance even in crossfire, so NO the OP couldn't get 4K as they want. Further (if you read past one single point you wanted to TRY correcting me on) "We have also created two bar graphs comparing the average framerate at 3840x2160 with 2X MSAA and "Ultra" settings with HBAO, and also at 4X MSAA." as the OP asked for, and we see a SINGLE 'non-throttled' 290X scores ONLY in the 30s then in the 20s when going 4X MSAA. SO OP "Will 2 R9 290's be sufficent for 4k gaming? Ultra setting and 30FPS+" , NO the OP would have to either go 2 R9 290Xs OR just a single
R9 295X2 and would be able to perform in the manner the OP would want.
Third point, YES he would be needing to "going for the 295x2" and that still would be MINIMUM 1350W, which would be unrealistic. Even in the second article they said " Note that our system runs lean, we do not have an optical drive, we have only one SSD, everything on the motherboard is turned off except what we need. The two major power drains are our CPU which is an overclocked Intel Core i7 3770K at 4.8GHz and the GPUs." and "We had no issues with this power supply and one AMD Radeon R9 295X2 video card." So if they turned on everything on the motherboard, added the optical drive, and say TB drive(s), add on several other things (case fans, cooling systems etc.) and they "would have issue" with the PSU being only 1350W.
So again, where are you reading otherwise to match the OPs question?