Area-51 R3, PSU + dual 1080ti

850W should be enough but keep in mind that dual 1080Tis draw around 660W. So looking at the specs you posted it would appear that the 850W PSU is not enough power. Whereas the 1500 should be more than enough.

That was my feeling. It might not be enough. The Funny thing is, they assured me that the PSU would have been able to handle the 2 GPUs and the rest of the components.

@Tesla1856 

Maybe the 50% gain applies to games?
In my case, doing 3d renders, I can definitely tell that with one GPU the render time has literally increased by twice: a render that would take, say, 1 minute now it takes 2.

Also, I don't use SLI as for GPU renders that is not needed (it seems it actually decreases performance).

But yes, to your point the full-throttle thing make sense: the moment I start real-time viewport render where both GPUs are at work that's when I get errors in Blender/Cycles.

So, if that's the case I don't understand how Dell could sell a PC with this PSU assuring it's able to handle two GPUs when in fact, it can't. And for the record, I informed them about the usage I would do with the PC so not quite sure what happened there.

Saying "two GPUs" is one thing.

But I think two GTX-1080ti cards running full-throttle (like while gaming) is quite a different situation.

Could be lack of power. Could also just be SLI in general. One GPU is better now-days. And you know, (when configured as SLI pair) you only get about 50% performance of 2nd GPU anyway.

A "smaller" pair (like 1060 or 1070) would likely barely pass fine.

IIUC, they shipped it with only one 1080ti and the 850w PS (which is a valid config, AFAIK).

Don't mean to beat it to death, but you said you don't understand how. I think that is how it happened.

@Tesla1856 What I meant is that I can't understand how they would guarantee that the PC with that PSU would be able to support a second GPU dedicated to 3d renders.

I first asked Dell Business representative and I would probably be OK with some confusion about technical aspects from that dept but then their technician confirmed the same thing too. So, that I don't understand it.

The online builder won't throw a "config error" since it was 1 GPU on the 850w PS (as built and shipped).

Sales people don't know everything. I don't even know everything. I do know I always get the biggest PS available (especially if I had your plans).

Even if you were actually talking to Business rep, not sure how they could say that because the Area-51-R3 is NOT a business-class machine.

And that gets to the final point ... for professional 3D animation and rendering work, I think a Dell Precision Desktop Workstation is the proper business-class machine for this use-case/work-flow.

@Tesla1856  I appreciate you're trying to help to understand the "why" behind this situation, but I hope we're not going in circle.

The online configurator is not the problem, that is why I directly talked to someone.

As I said, I wouldn't expect a business rep to know everything that is why I asked to talk directly with a technician. Now, if even the technician is not enough to make this sort of decisions, well that's pretty messed up.

As for the Precision VS gaming thing, the main advantage you would get as far as GPU goes is, well, precision and stability, two things in my industry are not top priority (Octane users know what I'm talking about).

I owned Quadro GPUs, and it's been a waste of money. It's those type of cards you would use for a particular type of calculations (engineering stuff and so on). For motion graphics/3d renders a gaming PC works just fine (that's what almost everyone builds these days for my type of work). The heavy lift is done on the GPU side, but precision is not mandatory (in fact, it doesn't add much at all). I know some people use Quadro GPUs for VR I think, but that's not what I do, so I wouldn't know the details.

Well, the only conclusion I can arrive to is that I've been sold something that didn't match the request despite the guarantee it would.

As an aside, I mean yeah personally I wouldn't run two 1080ti's on an 850W PSU.  Keep in mind Dell did sell SLI 1080ti's on 850W PSUs in the Aurora lineup.  Anyway, I came on to say that I don't think there's enough info to conclude that the issues you are experiencing are due to an issue with the PSU.  I mean, sure, it's possible, and I'm definitely not saying 850W is an ideal PSU for your use.  Most people would probably agree you're at best between borderline and underpowered. But even if the issue goes away when you remove one of the GPUs, the problem could still be related to the GPUs together, just one of the GPUs, the vRAM, the drivers, a slot, the cables, the bridge, the board, etc.  You really can't conclude it is the PSU just from this.  If you upgraded your PSU and the problem went away, then that's one thing.  But removing one GPU and the problem going away isn't sufficient to conclusively determine it was the PSU and rule out all other factors.  

I'm testing the PC with one GPU at a time. I run the PC for the whole day with one GPU without any issue.

Now I removed the first GPU and plugged in the second one (each test with the GPU in their respective slots). I'm testing it and stressing it and so far still no issue.

I'm not inferring that the problem is the PSU, but I would exclude the driver or else I would have already gotten some errors. The board doesn't sound the problem either as I'm running each GPU on separate slots.

So, to your point, you're right: the problem seems very possibly related to the two GPUs together though the possible conclusion at the moment seems to be the PSU.

So, this is the (Delta made) Dell OEM 850w MODULAR PS ?

Let me ask you:

That GTX-1080ti, what PCIe-Power plugs does it require? Two 6-pinners or what?

@Tesla1856 The power plug is 6+2

@Cass-Ole Right, I'm asking friends who are used to build PC, and they're all confirming that 850w sounds indeed under-powered for the task.

Thanks for the eBay links. Apparently there's some test and tinkering to do, not exactly my comfort zone (one of the reasons why I went with a pre-built). I'll look into that.

On the configurator / sales page (for A51-R2), you could not pair dual 980Ti or dual Titan X (250w TDP each) to the 850w, there's no way they'd allow / sell dual 1080Ti either, where the 1500w would've been mandatory at checkout

Aurora lineup got dual-1080Ti, only because the CPU was like a 95w TDP part; Intel-based 51's had ~140w TDP CPU & the AMD R3 has a 180w TDP CPU > the higher TDP CPUs are why u couldn't order 250w x 2  / SLI, the PSU wasn't enough due to its multiple 12volt rail design. If you hear people running dual 980/1080 Ti with an 850w, chances are it's an aftermarket type with a single 12v rail & no overclock on the GPUs & certainly not paired to a 180w TRipper CPU (if it had an Intel-eXtreme CPU chances are it isn't oc'd either) 

Regardless, the 1500w is part# 800GY

Maybe look into the Aurora's 1000w (0WTGN)(currently two for sale/eBay), it has 10Amps extra on the CPU rail & 4Amps extra on the GPU rail vs the 850w, it might be enough (max combined power on 12V A B D = 912w)(850w > max A B D = 792w), you'd have to buy one, test it & see (if no good, sell it & buy 1500w)(if good, sell the Aurora cables that u won't need & get some $ back)

800GY is useless without a set of matching cables for the Area 51

@DELL-Chris M  might have the part numbers for the cables as well as the 1500W power supply.

"800GY is useless without a set of matching cables for the Area 51"

51 R3 w/ 850w PSU > unplug all connectors from old PSU's front panel & back the chassis out > insert new 1000w/1500w chassis into case & plug all connectors back in & hit power 'on' button

An 800GY/0WTGN chassis is only useless if the case has no original cables (& seller has provided none); an owner with the factory 850w has always been able to upgrade to the 1500w --> simply re-use the stock cable set that came w/the 850

1500w might need a special server-grade C19 5 15P wall cord (part# 2R328) if seller can't provide it

If not enough video cables came with the 850 to do SLI/X-Fire, then owner should run the part tag / part# on their video cables & try to find them online or chat/call Dell for that extra set (example part# XFGRF). In this instance the owner has both sets of vid-cables & all other cables needed to do this swap > purchase a bare chassis (1500w will need a C19 cord) & install it

Note: A51 R5 (R6?) R7 should come with black cables