Dell Optiplex 990 MT PSU Upgrade

No it wont work because its ATX not EPS12v and the output for the 3.3v /5v rails is not 150W combined 25Amps.

Bare Minimum recommended working unit is EVGA 700BR

https://www.evga.com/products/product.aspx?pn=100-BR-0700-K1

https://www.bestbuy.com/site/evga-700w-atx12v-eps12v-80-plus-bronze-power-supply-dc-dc-technology-black/6346160.p?skuId=6346160

Hi speedstep, I can't buy that as the linked PSU is out of stock and has been for ages. Hence me trying to find a PSU in stock for under $100 that will work. Thanks for replying but OUT OF STOCK doesn't help me and I can't figure out  the whole rails thing you good people keep mentioning in similar threads.

I linked the same one at best buy.  Its available today in some places.

However everyone will have shipping issues so I suggest you go look for one.  3.3V 24AMPS is the critical spec along with the 150w combined.

Power supplies are not a single spec of WATTS with a single rail of 12V.

EPS12V  80 PERCENT EFFICIENT is required as is 24 AMPS 3.3V

and 150w combined for 3.3V/5V Rails.

https://www.bestbuy.com/site/evga-700w-atx12v-eps12v-80-plus-bronze-power-supply-dc-dc-technology-black/6346160.p?skuId=6346160

Same office depot

https://www.officedepot.com/a/products/6811224/EVGA-700BR-Power-Supply-Internal-120/

https://www.bestbuy.com/site/corsair-cx-series-modular-cx750m-750w-80-plus-bronze-atx-power-supply-black/8324202.p?skuId=8324202

https://www.amazon.com/Corsair-Certified-Modular-CP-9020061-NA-Refurbished/dp/B07HM869MP/

Corsair CX750 has 25AMPS listed on 3.3v Rails.

Most of the RM-x series also, but sadly, they are not made by EVGA.

The 8900 case cannot take many of the RM-X series because the length of the power supply is TOO LONG.  On the 990 the issue will be that the optical drive won't fit because the PSU wants to sit too far forward in the case. 

So thats bad advice for a power supply.

It will impact the USB ports in the top of the case and therefore not FIT into the case.

This post shows a clear picture of the issue.

The one that fits into this XPS unit happens to be EVGA 750B1 which is also fine for most Dells but its hard to find now for some reason.

https://www.dell.com/community/XPS-Desktops/XPS-8700-Compatible-PSU/td-p/6072480

https://www.amazon.com/CORSAIR-RM1000x-Certified-Modular-Supply/dp/B015YEI7LK

corsair cx750 is ok

https://www.amazon.com/Corsair-Certified-Modular-CP-9020061-NA-Refurbished/dp/B07HM869MP/

with covid 19 anyones shipping is likely delayed to june or july.

Get it as soon as Monday, June 15 - Tuesday, June 16 if you choose Two-Day Shipping at checkout.

All links are to SOLD OUT and OUT OF STOCK. No luck for weeks now. I wanted to buy a compatible PSU this weekend.

I have a used EVGA 600BR. Will that work?

It's not stated what GPU card you want to power, if that's the case.

EVGA 700B1 models are still in stock.  If by chance it's not when you check the link, search in Google "EVGA 700B1."  https://www.amazon.com/EVGA-BRONZE-Warranty-Tester-100-B1-0700-K1/dp/B018JYHBE6 

Not upgrading GPU right now. Just running 2 bluray burners and 2 4TB HDD and want to move beyond the stock PSU for future upgrades right now. There is no way in the world I am spending $249 for a PSU either.

600BR might work

https://www.evga.com/products/product.aspx?pn=100-BR-0600-K1

But not with 75W video card.

The reason I say might is because you have to take the AMPS rating on the label with a grain of salt.

It says 12V  50 Amps which is 600W. If you could use the MAX AMPS on every rail then it should be MORE than 600W rated.

It only says 130W for the 3.3v rails and yet it says 24 amps and 20 amps.

20 Amps @ 5v = 100W and 24 Amps @ 3.3v =75W but it DOES NOT SAY combined max 175W.

I have been running a EVGA 600B the last couple days with no issues. Maybe it's possible to use something with the same specs after all