Dell Optiplex 990 MT PSU Upgrade

Also...  as you can see by this benchmark, my system is actually performing above expectations.  If it wasn't getting enough juice it couldn't do that.  I also have my GPU overclocked by 150MHz and the VRAM by 1000MHz.

https://www.userbenchmark.com/UserRun/27833158

Just to interject my experience...  I have a 790 MT with an ATX EVGA 450BR, and it works perfectly.

How is the 990 different from my 790 in that regard?

https://www.evga.com/products/product.aspx?pn=100-BR-0450-K1

The 400BR has less than 24 Amps on 3.3v and less than 150W combined.

There is a user with RM550 power supply and 75W card having issues for the same reason.

3.3v @ 20 AMPS =66W   3.3v @ 24 AMPS = 75W   combined matters because you are not JUST USING 3.3v you also use 5v rails and 5v standby.  You cannot use max amps on all rails simultaneously.

I know what works and I know what is a problem.  This is based on direct experience with the models involved because I own them.

YMMV  use under spec power supply at your own risk.  But if you go too cheap the psu can blow up and FRY everything including HDD, CPU, RAM, Video Etc.

400BR SPECS

And here is a comparison of My EVGA 450 BR with the Dell PSU it replaced.

The EVGA has 20 amps on both the 3.3 and 5 vs 10 on the 3.3 and 13 on the 5 with the stock Dell PSU it replaced.  As well as the fact that a higher end EVGA 450 watt gold has the same 20A for each, but a combined of 100 watts.  20 less than my 450 bronze.

https://www.evga.com/products/product.aspx?pn=123-GM-0450-Y1

Here's a photo of the label on the Dell for your reference:

I respect your opinion, but no resonable person would use a 600-700 watt PSU for an i7 2600 and a 1650 Super.  And why would my 450 BR have 2x PCIe 6/8 pin power connections if it cannot provide what's needed?  My 1650 Super has a TDP of 100 watts, and requires 1x 6-pin power cable.

With all due respect...  these seem like your own personal standards, and the vast majority of system builders would disagree with you.

"By your arguments the PSU's that Dell include cannot even power the PCIe slots they include. You're not making any sense my friend. You're simply just throwing numbers around."

I'm not throwing numbers around. The ripple and noise must be low on all outputs, but especially on +3.3V and +5V combined rails used by PCI-E slot, RAM , SATA and CPU. 

The EPS12v spec was updated to include increasing the 5VSB power from 4AMPS to 6AMPS

And the Combined power for the 3.3v/5v rails to OVER 150W.

This is not throwing numbers around.  Power supplies have more than 1 rail and more than a SINGLE spec of WATTS.

If you look at the max AMPS on each rail you will see that if you could use the max AMPS on every rail simultaneously that the rating would be higher.  VOLTS X AMPS = WATTS

300 WATTS for 12v = 25 AMPS.

5v @ 25AMPS = 125W

3.3v @ 25 AMPS = 82W

3.3v @ 20 AMPS = 66W

Dell 875W power supplies INCREASE the 3.3v current to 30AMPS and the combined power to 225W. DELL W299G power supply

This is not throwing numbers around this is the SPEC for the power supplies.

https://www.amazon.com/Genuine-Dell-Precision-Workstation-Compatible/dp/B0097DON18

This unit is also used on some of the Alienware and precision models.

5v @ 4 Amps is 20W

5v @ 6 AMPS is 30W

5v @ .9 Amps for 8 USB3 ports is 36W

5v @ 32 AMPS is 160W which is the EPS12v 2.92 update spec.

EPS12V is defined in Server System Infrastructure (SSI) and used with current Core i3/i5/i7, and Xeon.

DELL 875W Spec

The point remains...  any modern 80 Plus PSU is going to out-spec a Dell PSU from 2011-2012 in every regard.

3.3v @ 10 amps is 33Watts

3.3v@ 24 amps is 75W

The 700BR is chosen based on the max output spec for the 3.3v rail and the max combined spec for the 3.3v/5v rails of 150W  not 90 to 130W which is not sufficent.

There is a user with RM550 power supply having issues with a 75W video card for that very reason.

This is also why the GT1030 doesnt have an issue and the GT1050TI does.

Any of these modern 80 Plus rated PSU's are rated well above the PSU that comes with any Optiplex out of the factory.  I own 2x Optiplex 790's.   I use a MT right now, and I also have an SFF with an i5 2400 and a 1050Ti LP.  That SFF has a Dell 240 watt 80 Plus gold, and runs the i5 and 1050 TI perfectly together at peak performance. 

By your arguments the PSU's that Dell include cannot even power the PCIe slots they include.  You're not making any sense my friend.  You're simply just throwing numbers around.

I meant the +5sb in my last sentence.

Also, I notice that with a EVGA 700 watt gold the +5 is even lower at 2.5.  So it would seem the lower that number the better.

https://www.evga.com/products/product.aspx?pn=100-GD-0700-V1

The other spec you are ignoring is +5VSB

4.0 A or more +5 VSB is required for power supplies in systems supporting ACPI S3 power state

This is only 3A on the 450BR so there is another EPS12v not up to spec rating.

450BR

I'm really not trying to argue with you here, but you keep missing the larger point.  That point is that my Dell 790 MT is 9 years old, and it lived a perfectly healthy life for all that time with the stock PSU, and now it has a much higher rated PSU with the 3.3v, 5v and 12v, and you're trying to tell me it's not good enough. 

Also, any standard following blue 16x slot is rated to carry 75 watts without external power.  Hence why cards with a TDP above 75 watts need a 6 or 8 pin.

You even claimed a 1050 Ti wouldn't work, yet they do.  Just go on youtube and look.  There are many videos of people using a 1050 ti in a Dell Optiplex. 

Also, even the 700 BR still only has 3A on the -5.

"The point remains... any modern 80 Plus PSU is going to out-spec a Dell PSU from 2011-2012 in every regard." This is wrong.

Dell designs using EPS12v 80 percent efficient units to meet energy star requirements.

20 July 2007: Energy Star Computer Specification 4.0 goes into effect. The specification requires 80 Plus power supply efficiency levels for desktop computers.

https://www.techpowerup.com/articles/160/images/EPS12V_Spec2_92.pdf

Dell only supports their power supplies.

Dell puts a limit of 25W for the Video slot for non Tower systems and designs to 40W max for the Tower models which is why there is an 8CCF1 GT1030 video card spec for specific models.  Units that have 75W or greater video card have OPTIONAL 365W or Greater power supply. The other gotcha with these systems is that they use PROPRIETARY 6 or 8 pin connector and power supply size for the 3650, 3670, 3020,7020,9020,3040,7040,9040  G5 series etc.

Your statement is nonsense. The current available and combined power for the 3.3v/5v rails is not trivial.

The reason for recommending specifc models of power supply like EVGA 700BR being ok and 450BR being not ok have to do with the actual spec for the PCI-E slots and 3.3v/5v combined as well as max current for the 3.3v bus.

EVGA 750B1 is fine but B2 BQ G2 N1 W1 versions from the same vendor are not fine.

Corsair CX750 is fine but CX450 CX650 etc is not ok.

This is also why 70 percent ATX spec is not acceptable because 80 plus requires 90 percent PFC.

Also, I notice that with a EVGA 700 watt gold the +5 is even lower at 2.5. So it would seem the lower that number the better.

No thats Nonsense.

Power Requirement on specific bus is based on Design.

4 AMPS is required for S3 ACPI.

load, the +5VSB rail matters,   +3.3V/+5V combined matters

your statements are bad advice at best.

EPS12V 2.92 is a specific, non-ATX standard

EPS12V 80 percent with 90 percent pfc is not compatible with standard  ATX12V 70 percent non pfc.

The power supply shall have current limit protection on +3.3 V, +5 V, and +12 V rails.

5 V & 3.3V combined wattage of 150 W is required. Higher wattage units this goes up to 160W.

The combined output power of all outputs shall not exceed the rated output power.

Load ranges are provided for each output level. The power supply must meet both static and dynamic voltage regulation requirements for the minimum loading conditions.

Table 34: 450 W Ratings Voltage

Minimum Continuous Maximum

+3.3 V     1.5 A           24 A

+5 V        1.0 A           24 A

+12V       1.0 A           18 A 

This is not throwing numbers around its based on Spec as well as Safety.

Any Recommended supply REGARLESS OF WATTS should

Meet Intel SSI EPS12V 2.92 specifications
have Active Power Factor Correction (PFC) function maintains power factor > 0.9
Be High efficiency 80 percent
Have Over voltage & Over current protection
Meet UL (safety) and FCC class B (EMC) approved , Energy star 4.0

if you do not provide at LEAST 24 amps for 3.3v and 150W combined for the 3.3v/5v rails and 4 AMPS for 5VSB you will have issues with 75W and greater cards.

each 6 pin pci-e connector represents 75W on the 12v rail.

each 8 pin pci-e connector represents 150W on the 12v rail.

you cannot have max current on all rails at once.

If you add up the output from 450W unit then 2x 6 pin connectors means 150W from 12v rails and 300W for EVERYTHING else.

This contradicts getting 20W for 5VSB and 150W for 3.3v/5v combined as well as 18 amps on 3X 12v rails from the 24 pin connector.

18 AMPS 12 Volts is 216 Watts

3 RAILS @ 18 AMPS IS 648 WATTS

450BR

DELL 875