Area 51 R4 4x GPU's?

well, the SrvcManual has the layout (left), see the separate Specs Manual (right) which explains PCI-Xpress lane assignments, they list up to triple Grfx because as you noticed the PSU only has x3 Grfx sets = 6 power cables

Y-splitter types might include dual 6's or dual 8's (eBay search term might = 8pin splitter dual)

Below, I'm not explaining this to you so much as working this out for myself, I need to see it on paper, lol

Each 6+2 (8pin) connector you have is rated for 150watts max by ATX standards, x2 available = 300w > (a 6pin is rated at 75watts)

A 375watt card, pulls 300w through the cables, 75watts through the PCI-Xpress lane itself (the gold teeth), so they say, that is because 75watts is the max PCI-X lane spec + 150 for each 8pin = 375w which complies w/ATX standards

- some manufacturers flaunt ATX standards, say a 500watt card with just dual-8pins -

A straight forward calculation suggests that card 1 card 2 receive x4 of the cables, card 3 card 4 get splitters:

• x2 Ti = 500w or about 425-450watts from Grfx cables / 50-75watts through PCI-Xpress lane, give or take
• the math is ~125-150watts out of Spec, can't support a safe use of a splitter pair so I would not recommend it be tried

Above, assumption is FE-type 8pin + 6pin Ti, now a different scenario > card 1 2 3 4 get cable 1 2 3 4, cable 5 6 = splitters

• Ti, based on whose card you use (it's unique power delivery needs) will pull 'some' of its 250w rating from PCI lane
• if the Grfx card exceeds 225w from the cables, the power supply will probably shutdown & restart (remove the over-load). the only question is 'when' or at what wattage? That's up to the power supply to figure out, not me

Left Image: Tri-Ti + 1080 (Ti #2 Ti #3 on paper get 225watts from cables, anything over that might trip PSU)

• an 8pin + 6pin Ti might consume less power than a dual-8pin type
• again, we rely on the PCI-Xpress Lane to feed the card some of its 250watt rating, so for cards 2/3, they have 225watts available in the cable (on paper >150+75)
• 'staying in spec with the cable rating' is different from 'staying in spec with the power supply'
• power supply will decide how many watts it will allow to go through x6 cables, I don't have the real figure, just estimates

Right Image: dual-Ti + dual-1080

• cable set appears to support x2 Ti + x2 1080 > solo-8pin type 1080s = no need for a splitter > 'on paper it works'

What can the side label tell us?

12V A-D 32 48 48 16 = 144a x 12v = 1728watts, yet shutdown should occur at a lower 1440watts as stated

therefore x2 48Amp Grfx rails = 96 Amps = 1152watts, it isn't as simple as expecting that shutdown happens only @1152watts+, other factors will probably not allow the Grfx to pull all 96Amps, it might depend on what 12VA 12VD are pulling at any given moment

• 1728/1440 = 1152/X > X = 960
• 12A 12VD = 32+16=48AMP > it is essentially x3 48AMP rails, or, 1440watts max / 3 rails = 480
• 1440 - 480 = 960

When the Grfx push the power supply over 960watts, you're on borrowed time relative to rail 12VA 12VB, because your CPU wants to be overclocked also probably, which will trip the rail 1st, Grfx?, or CPU?

• x4 1080Ti = 1000w on paper for the FE model
• some of that 1000w is fed by PCI-Xpress lane, check rating of MSI ASUS GIGA EVGA etc, are they rated over 250w each?

What does it look like?

• x6 Grfx cables rated at 150watts per 8pin = 900watts allowed per ATX specs
• 1000watts of cards, some watts fed through PCI-Xpress lane > 900watts through cables / 100watts PCI-Xpress lane
• the tripping point of the power supply will be somewhere between 900watts due to ATX cable specs, or 960watts - 1152watts on paper from the dual-48AMP rails
• again, I suspect that an 8pin+6pin Ti is preferred here over a dual-8pin
• the CPU itself will crave 12volts, therefore, the system is about maxed out with quad-Grfx

It Looks Like 'Maybe'

Seek a 2nd opinion from elsewhere, join the GeForce forum, if you're after EVGA vards then try their forum etc, the side lable is there to share with people, it has a pair of 48amp Grfx rails, combined 12volt output on all four rails is 1440w max. Don't hold me to the numbers and details, they're rough guesses mostly

AfterMarket Power with plenty of cables and single 12Volt Rail?

JonnyGuru runs the top PSU website online, he works for Corsair, I explained that ax1500i won't work in Area-51 R2, he visited the Alienware factory in Taiwan or HongKong when he was on a junket, took some power supplies in, was allowed to test a few, ax1500i ax1200i Hx1200i failed to work due to a Bios timing issue measured in micro-seconds. No idea if R3 R4 have same issue or not, a person would have to try (failed compatibility is a 'click' when system turned on)

EVGA 1600, 1300 or a similar model from another brand might work. You'd buy the factory 850watt included in price (keep it or sell it) then self-install a capable supply with enough cables to power it all. If you buy the 800GY 1500watt and it fails to perform, it has re-sale value you can put towards an aftermarket type

• 850w is estimated to account for approx. $150 of the $1900 base price > add $250 for 1500w = approx. $400 invested
• EVGA 1600 is a search term you can put into the forum search box 

Tell your client that the guy in the forum said 'maybe', & can not agree to anything accept that Ti + 1080 (single 8pin) looks ok, where any configuration over that ventures into the unknown due to use of splitters so you're waiting on a 2nd opinion

Thanks again Cass-Ole! I guess the max possible with stock PSU is x2 1080Ti + x2 1080s.

I re-thought some things. My 1st graph was from a day ago, a day later a lightbulb went off & I made some other graphs, see my edits in the 1st post

Your basic 1080Ti (FE or entry-level card) has an 8pin + 6pin, rated at 250watts. An aftermarket card might call for 8pin 8pin (dual) in the expectation you'll overclock it or they will OC it for you (ie go over 250watts). The major portion of watts go through the cables, the rest through the PCI-Xpress lane, I don't have exact figures. In my charts, any card that surpasses 225watts through the cables puts you in the red-line, on paper at least, so to keep the power supply from shutting off / restarting with this many cards, we might try an FE type of card or a derivative of one, any card that has an 8+6

Whether 8+6 or 8+8, I'm assuming the cards won't be overclocked, in order to keep things in the red-line but not over it. If shutdowns / restarts occur, you broke the Speed Limit, you've overwhelmed the power supply > either remove overclock, remove a card, or replace power supply with aftermarket type that has more cables & a single 12volt rail

an interesting dilemma

Area-51 Grfx cables are 6+2's

*As I understand it, 75watt rated 6pin pulls 12volts from pin 1 & 3 only, pin2 simply is not used, pin 1 3 draw 37.5watts each, note there's only x2 Ground wires in the 6pin also

*For a card that has an 8pin, when you insert the 2pin section of your 6+2, the Grfx card is authorized to tap pin 1 2 3, then Ground out through x3 wires now (3 in 3 out), the wires then = 50watts each across 1 2 3 = 150watts

*Notice how if you do not insert the 2pin, the 8pin card fails to work, by design; the card assumes the power supply 12volt rail can not handle it > ie pin2 may be disabled inside the power supply, cautionary to prevent people using inferior PSU w/high power cards

What interests me about all this, is I suggested trying an 8+6 type of 'entry-level' Ti in order to keep power 'reasonable'

One graph suggests using splitters on the Ti 6pins, right? Pull 150watts through cable 5, divert 75watts to one card, 75 to other. Hmmmm. This assumes, and I make the assumption without actually knowing, that the 6pin of that 8+6 is, well, going to cheat a little bit & act like an 8pin & draw 12v across 123 & Ground out through x3. But what if it acts electrically like a true 6pin instead? That's the dilemma > example card #1 will try to pull 75watts (on paper) through your cable, card #2 will also, you'd use a splitter, but, what if that now 150watts is being called on from what we learned prior about how a 6pin behaves, it pulls 12volts only across pins 1 & 3 ... so what happens when two cards are trying to each pull 75watts (now 150watts) only through pins / wires 1 & 3? In effect we're back to the same issue as Graph #1, put the cable out of spec  

for a card that's an 8+6, the above 6 > x2 6 splitter is probably best (buying an 8 > x2 8 does nothing)

On the one hand, if the card's 6pin port behaves just like an 8pin would (they've designed the 6pin to kind of cheat a little & grab up to 75watts over 3 wires as the 8pin does), then there's no issue with a splitter, but

• if it behaves like a true 6pin, then the use of a splitter is actually a bad idea if you think about it
• how does NVidia & its partners electrically wire the 6pin port of a card is not something I know since I do not use NVidia products, nor is this a question I've ever heard asked before

if the 6pin port of the card is designed not to grab pin 2, & behave like a 6pin would normally behave?

 what happens when two Ti 6pins try to grab 75watts over just pins 1 & 3

that's a dilemma, the splitter wires might burn up

I wish I knew, but I don't

Go back & look at the little 6pin diagram again. Now look at the Graph. Example, bottom card 1 then card 2 running off cable 5 + splitter? If those cards are an FE-type 8+6, if the 6pin is designed to only draw 12volts through pin 1 pin 3, then asking card 1 card 2 to try to pull 75watts each (150watts) just through pin 1 pin3, it looks like an overload to me

*Understand that just because cable 5 is a 6+2, and even if you buy an 8 > 2x 8 splitter (a dual 8 splitter), that's meaningless in the end if you're only using it to connect to a 6pin port

*Remember, it's when you insert the 2pin, only then is the Grfx card authorized to draw 12volts over pin 1 2 3

*In otherwords, since the 6pin port can not receive a 2pin, the 6pin might not draw from pins 1 2 3, but just pins 1 3, make sense? 

But. If the 6pin port of that (8+6) Ti simply grabs 12volts over pin 1 2 3 like the 8pin port next to it does, then this is a non-issue. It's for that reason I might raise this issue in a GeForce Forum or similar > Crypto Miners & quad-SLI owners surely face these problems & may have answers on what to do, or which card is best to buy

___________________

so in a world where we never get an answer for this, what to do?

Simple

Buy the dual 8pin cards

8pins make use of all the x3 12v x3 Grounds, so, that's less stress on the splitter, but those dual-8pin cards might actually draw more power, & put you deeper into the red-line which is itself the prior dilemma which prompted me to suggest the 8+6 entry-level cards, which, might be bad in tandem with a splitter. But might not, it depends. The variables, factors & unknowns have compiled on themselves to the point I'm not comfortable in telling you any of these configurations are going to be ok or not, short of the original dual Ti dual 1080 looks ok, the rest of the configs are a step into the unknown, I don't know how to be any more clearer than that

No one at Alienware's going to authorize you to push in 4 cards with splitters I wouldn't think

The OriginPC forum? A consultation or call with them instead? They might have an opinion (=

Do not make a purchase that costs thousands of dollars based on what I said, seek a 2nd opinion