will the ASUS ROG GeForce GTX 1070 STRIX-GTX1070-O8G fit in my R4 chassis?

my 290x is 11" to the end of the PCB, 13.5" w/the stability bar. Technically, any card over 11" - 13.5" could fit, so long as nothing gets in its way in the wall area between the PCB to the fan, so you'll have to measure & look in your case for obstructions. I think we decided that 11.25" was the factory spec, anything over that is a user gamble so buy from a source that accepts easy returns

875watt R4 pwr supply was sold with solo-TitanZ, it's enough for 980Ti /1080Ti / TitanXp, so you're good if u have the 875

If the card has a single 8pin power port, if shutdown / restarts occur (they shouldn't, but if they do) & if it doesn't come with a dual-6pin to 8pin adapter in the box, I'd think about getting one, hook both of your 6pin vid-cables to it (blu-wht + blu-ylw) so it runs off of both 12volt Grfx rails (prevent shutdown / restarts by adding your 2nd power cable), that is if it fits. You can ask the question on Alien Arena if you need a 2nd opinion. If the 5.25" width does not allow the PCI shroud to close then remove the shroud. Cards over 11.25" require a source with a liberal return policy, hope it works out

• https://www.ebay.com/sch/i.html?_sop=15&_osacat=0&_odkw=evga+cable&_from=R40&_from=R40&_trksid=p2334524.m570.l1313.TR0.TRC0.H0.Xevga+6pin+8pin.TRS0&_nkw=evga+6pin+8pin&_sacat=0

ROG STRIX-GTX1070-O8G-GAMING | Graphics Cards | ASUS USA 

It would be tight if it fits AT ALL.

Power Connectors 1 x 8-pin (so dual 6 pin to 8 pin adapter would be required)

850w POWER SUPPLY would be recommended.

460w POWER SUPPLY would be pushing limits.

Thank you for the great info!

this will help a lot

Could you suggest a 6 pin to 8 pin cable/adapter I would need to order?

Follow the link from prior post for black EVGA dual 6's, the cheapest result #1 is fine > New eVGA Dual PCI-e 6-pin to PCI-e 8-pin PCI Express Video Card Power Adapter:

https://www.ebay.com/itm/New-eVGA-Dual-PCI-e-6-pin-to-PCI-e-8-pin-PCI-Express-Video-Card-Power-Adapter/112525413084?hash=item1a33098adc:g:wBEAAOSwne9Zkfo6

An 8pin cable is rated up to 150watts while a Grfx card will pull X amount of watts from the physical PCI-Xpress slot through the gold contacts / teeth, 1070 might be a 130 through cable / 50 through Xpress scenario, a ratio similar to that which I pulled out of thin air (but it can't exceed 75watts by ATX standard)(on paper a 300watt card will pull 150 by 8pin / 75 by 6pin / 75 by Xpress slot), so we have a bit of faith a solo 8pin in your rig is enough, will handle upto 150w of the Strix 180watt demand. Since it's a dual-12volt-rail design we might like to balance / share the load between them, funnel both Grfx rails through a 6pin -to- 8pin adapter so that neither rail wants to output say over 100watts each when overclocking the GPU or peak power demand when gaming / getting down to b'ness. You can save $7 & test without one, grab one later if the power supply rail acts like it wants some load sharing help from its unused partner rail. Again, I can't confirm the card fits, but it might > 3/4" longer than mine & an inch wider > u might have to stick it in to find out