FYI: with the edit function u can change your post title to 'Aurora R5 Power Supply Size', so clickers know what the query is

It does use a standard size of W 150mm x H 86mm | 5.9" x 3.4", where length / depth is the variable which changes based on size / output etc. Their 460w is about 5.5" long while their 850 is 7.5" long. Both of their power supplies will have short manageable cables while an aftermarket chassis may come with long cables (one size fits all), where a swap from theirs into a new one requires diligence to cable manage any new cables while being mindful the swing-arm has to shut fully & the side panel go back on, therefore care is warranted when installing a new chassis with new cables ie 'work slow & think it through'

A comparison of the two power supplies. The EVGA 650 GS is a bit longer, at 5.9" x 5.9", but still a relatively small power supply which was one of the main reasons I chose it

above, 850i has x5 8pin ports ... how many of them are used depends on your hardware. The CPU & Video/Grfx/PCI-E ports are shared, meaning you plug a cable into any of the 5 & your mthrbrd/cards get the 12volts/grounds they need

Some 1080s get one 8pin (6+2) power port (Founders Editions). If you're buying that type of 1080, duals, then you'll deploy x2 cables to feed your pair + your CPU cable:

• x3 8pin modular ports will be used, x2 will remain open
• GPU_PWR can then get its own cable

Some 1080s (Asus Strix etc) have a pair of 8pins (maybe a 6pin + 8pin), or simply need x2 cables to feed their dual-power ports. If so, x4 of your 8pin ports will be used to power cards, CPU needs a cable also, & therefore you run out of ports to power GPU_PWR, ie the power supply isn't full enough on the front panel to power it all. I think we'd note that 850i is best suited to 1080FE cards

1000i has x6 8pin ports: it can power 1080 cards that use dual-power inputs, it can power the CPU port, it can power the GPU_PWR port, ie all x6 8pin front panel ports are there at your disposal

What is GPU_PWR?

It's supplementary power to the PCI-E slots / lanes, call it 'easy 12volt access' to the PCI-E lanes. The gold contacts (gold teeth) on your video card that plug into your mthrbrd also draw 12volts (that is provided through the motherboard 24pin ATX cable). To 'help' a video card get freer access to 12volts (normally coming through the 24pin ATX cable), SOME motherboard makers have an exterior port to feed the PCI-E lanes, in this example, Aurora uses an 8pin port:

• the stock 460watt powers GPU_PWR through a 4pin
• the stock 850watt powers it through a 6wire 8pin

If you use for example Asus Strix (dual-power) 1080s in tandem with 850i, I would simply leave the GPU_PWR 8pin port bare:

• note: chances are you're going to get a CPU cable that is a 4+4
• x1 '4pin' inserts into mthrbrd CPU port
• x1 4pin is 'open'

If you can obtain a 4pin extension? You might tap into that open 4pin, power your GPU_PWR with it, the same way the stock 460watt only uses a 4pin (in that 8pin connector)

Or --> if they give you a ribbon cable? Split it down the middle:

• send 1/2 of the 4+4 to the CPU
• send the other 4p to GPU_PWR

Note that Corsair sells individual cables ~$5 each), so if you're reluctant to burn a new 4+4 cable by splitting it down the middle, you can of course buy a new one & store it in your pouch

• corsair.com/en-us/power-supply-units/psu-accessories
• buy the 4+4 ribbon

above, top row, my 8pin male is a stand-in for GPU_PWR 8pin male ... bottom row is an empty 4pin male, a stand-in for Aurora's mthrbrd 4pin CPU port

• 1) the 4+4 females plug into 8pin
• 2) a 4pin goes into 'Aurora CPU 4pin', a 4pin stays behind for GPU_PWR
• 3) the 4pins can be 'switched', or, either 4pin allows a scenario such that CPU gets a 4pin, GPU_PWR at least gets a 4pin as supplemental power

Your options? Buy 1000i, or, any type name brand PSU with x6 8pin ports

Still want 850i & get power to GPU_PWR?

• then use 1080FE single 8pin cards, which leaves a cable open to power GPU_PWR

if using dual-power (6/8 r 8/8) cards (now or later)

• split the 4+4 CPU cable, send a 4pin down to GPU_PWR, I suppose it's better than nothing

I doubt 1080s need supplemental power, however Titan XP or newer 1080Ti cards might like GPU_PWR, so you have time to think this through I suppose. Maybe try 850i with 1080s, toss 1000i in down the road, later, if you go with 250watt+ cards (1080s are only 180watt cards)