Aurora R4, will this power supply work?

There have been examples of an Aurora R1-R4 owner installing the Area-51 R1 1000w 1100w 1200w PSU since both desktops 'share' the same PSU case harness pinout; those A51 PSUs are several inches longer than the 875w chassis so you'd remove the left-hand hard drive cage, see vid How to install Area 51 PSU

Generally, the Aurora & A51 875w 1000w 1100w 1200w PSUs are very similar in that they each have 18Amp Video Card Rails, yet it also depends on how many Video Card cables your case harness &/or the PSU has, where:

• x1 18Amp rail x 12V = 216w per cable x2 rails/cables = 432watts output
• the 875w, 1000w, 1100w & 1200w (J297R) will provide multiple 18Amp rails

Where:

• Aurora 875w & A51 1000w have two rails & two cables
• A51 (factory-ordered) 1100w has three rails & three cables 
• A51 1200w J297R has four rails & four cables (two in the PSU chassis)

1) Only factory-ordered 1100w A51s have that 3rd case harness cable to access that 3rd rail; so in the video, the person claims an 1100w went into that Aurora & yes the pinout is ok to make that swap but he couldn't access the 3rd video rail, not without the 3rd A51 'special plug-in' case harness vid-cable, & since Aurora has just two vid-cables?, that 1100w would act just like a 1000w ... if u tried the 1100w you'd need the 3rd cable but it has no place to plug into the Aurora case harness!, so no real point to buying & trying the 1100w, got it? True the rating is 100w over the 1000w but that's due to the 3rd vid-cable/rail you can't even use ...

2) In fact, because Aurora 875w & A51 1000w each have a pair of 18Amp rails?, they may as well be & are identical rated power supplies, there's no advantage to try to swap up to the A51 1000w ...

3) You could try the 1200w J297R, get four rails + four cables, but in a single-card scenario the extra two cables won't help exactly (it'd behave like your 875w: two rails through two cables plugged into one card etc), thus it may only make sense when using dual-cards (deploy all four cables into two cards etc)

4) The 'best' 1200w PSU is VHM5V, it would provide four cables on a single 'fat' 46Amp video rail & that single rail would power one or two cards ~the same, up to 46Amp x 12V = 550w

Your best bet is to test out your 875w (J556T or W299G) model 1st, see if it works & stays powered on w/out shutting off due to lack of powa, if so then look into J297R or VHM5V, & at worst just buy a Corsair or similar aftermarket PSU of sufficient power rating for your card(s)

Note: J297R is best used w/ two cards, VHM5V is the top choice for one power-hungry card but extra ok for two cards

Note: most aftermarket power supplies tend to have a single 'huge' 12v rail & do not live by rules like how many vid-rails or cables which dictate what u can or can't use etc., while multiple-rail PSUs do have limits based on Amps-per-Rail ratings etc

" ... trying to figure out why computer keeps shutting down during benchmark" 

You have x2 vid-cables (BLU-WHT + BLU-YLW) on x2 18Amp video rails (rated @ 216watts each); the side label spec says the combined x5 12v rails A-E shall not exceed 825watts total. A rule of thumb is a rail may / might exceed its rating by ~10% before shutdown (a 1000w single-rail might hit 1100w+ before shutdown) so these 18A rails might hit ~20Amps? ~240watts? Either x1 or x2 video rails exceeded 18-20Amps & shutdown (over-current protection / OCP kicked-in), or, the combined A-E exceeded 825watts +10% = ~900watts & shut-off, or any rail A-E exceeded its rating. Or a vid-card overheated & shutoff (I'm not saying it did). If it games ok, the PSU is still huffing & puffing for your needs. You MIGHT get away w/ an aftermarket PSU of 850watts (single 12volt rail type), more likely u need 1000w+. So more power means install new PSU, since to me, the 10+ year old 875w OEM is at its limit w/ those cards (+ CPU?)

A 'spec sheet' that does not originate from Dell/Alienware.com itself is sus, not sure where u got specs it could run a pair of 300w cards? Below is a 'factory' list of 'approved' (reference) cards as seen on the R1-R4 sales pages at the time, nowhere is there a spec that dual-cards can exceed 225w each (exception GTX 780 SLI) ... when cards go 295-300w each?, it's advised to run a solo card

*(example: ATI/AMD HD5970 @ ~295w ea was not an option in Aurora, for a reason, PSU not validated to run x2 in X-Fire), GTX 690 300w only sold as solo-card

*I think at BEST, GTX 780 SLI (250w each, reference) was the top sales config, to me = the Max TDP one can run as dual-cards on that PSU

"Is my 8 pin (6 + 2) connector & 6 pin connector each sharing 18 Amps? Since these two connectors are in parallel, would they be considered 1 x 12V rail?" ... Yes, each cable is on its own 12v rail, & each cable has x2 connector-pairs (6+2 150w & 6pin 75w = a 225w rated cable PAIR)(450w etc). I'll ramble for the next few minutes, do forgive. Now, I'm not surprised your spec sheet pic came from Dell.com Support, but frankly they're page is wrong (Last Published Date 21 Feb 2021 | Version 4, that's probably a clue). Suffice it to say, dual-300w cards were never a factory option, & they luv, LOVE to sell GPUs, the more Hi-Powa the more profit they make on it, but, never did sell anything better than say dual 780s (note there's no dual 5970, 590, 690 etc on this list, top cards like those weren't approved for sale in pairs, perhaps both as a powa + thermal issue they would not validate, warranty or sell etc) Alienware Aurora ALX, R1, R2, R3, R4, May Crash Or Experience Blue Screen Errors Due to Graphics Card Power Cable

True, some of the top cards on that list require dual-8pin connectors, so the original 875w is limited to dual-cards w/ a 6pin 8pin design, yet HD5970 was a 295w card w/ an 8+6pin design, perfect yet they did not sell it as an option in Aurora, & we'd suspect due to a thermal issue they couldn't validate / wouldn't warranty etc & so, 'dual-300w cards' in their specs seems a stretch to me (as does the 600w solo card! ... the cables are rated at just 450w), but the fact is, your PSU shuts off / restarts when both GPUs hit just 180+ watts (~360w total)? Dunno why, maybe age of PSU. Maybe the 24pin (non-video) 12v rail overloaded trying to supply the PCI-E lanes? Maybe the software figure isn't correct, which is an issue at times (false volt / watt readings are common in software). But 180 is way short of the 250+ watts (x2) we'd expect out of say 780 SLI. If u created a post about the Dell F1200E, I don't see your post, just a notification about it. A PSU swap may cure this shutdown/restart issue, if so, update us in the future

For better CPU cooling than your 120x27mm wide rad, check eBay often for the R4 01YGW cooler (~$50/used, 38mm wide rad) or look into H80i type coolers (38mm or x49mm wide rads)