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780, replacing the Dell 225w PSU
I have a Dell OptiPlex 780 mini tower .
Mine is a Dell model number L255EM-00 255 watt , has the test button on the back. Dell part P/N D326T. and a date code :R1103, serial NO:00005406. Also another P/N PS-6261-9DA-RoHs. I cannot find what date it was built .
More to the point , when someone replaces a Dell PSU with an ATX type isn't it true you need to get an adapter cable with plugs to adapt the ATX 24 pin to the smaller BTX 24 pin Dell uses ( I've seen them for sale on many sites). And if this is the case as long as a ATX PSU is rated at or higher especially the 5 volt and 3.3 volt combined is the same or higher than the Dell model and fits the mini tower case will you be good to go?
I'm not adding any extras other than one day a PCI express x16 graphics card. I don't need some high power PSU . It does have a western digital 1.0TB hard drive built 13 May 2012. The manufacture date or the I assume mother board is 07/22/2011 in use date 10/20/2011. I found this in the screen hitting F12 then F2 . I found a stamped in the metal date of 2016 on the removable side panel . Can I assume this tower (not the PSU) was built in mid 2011?
The company I got it from who refurbishes PC's cleaned everything even the PSU and installed windows 10 Pro x64.
speedstep
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September 8th, 2018 12:00
Non standard connection is the 24 pin. EVERYTHING Else is the standard.
Dell D326T does not have the mini 24 pin like the 780 does. The default 780 mt psu is 305W.
The following are the Dell OEM 305w PSU for OptiPlex 780 MT =
18N8R
CY827
MK9GY
PF3TR
P192M
M360M
WU133
https://www.moddiy.com/products/Dell-980-960-780-760-PSU-24%252dPin-to-Mini-24%252dPin-Adapter-Cable-%2810cm%29.html
Recommended power supply for mini tower is the EVGA 750B1.
https://www.amazon.com/EVGA-SuperNOVA-Modular-Warranty-110-B1-0750-VR/dp/B00K85X23O/
Same vendor B2 BQ GQ G2 do not work.
blues90
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September 8th, 2018 16:00
Why would I need such a high wattage PSU . I get the idea of having modular connectors and why I need the adapter cable for the 24 pin.
I was told by Dell that the 255 watt was standard and have seen a few videos showing this PSU . As far as I can tell the 305 watt is much larger than the 255 watt at least when I try to find info on them and what amazon sells as well as other sites.
blues90
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September 8th, 2018 16:00
It becomes confusing to me because I have read if you try to use a normal sized ATX 24 pin not only will it not fit the MB the leads from the ATX are not the same source of power from an standard ATX PSU.
speedstep
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September 10th, 2018 04:00
It will become very clear when you try to use a standard 24 pin that it DOES NOT FIT AT ALL. They also swap pins around so that you cant make an adapter that's just straight thru as you can see from the picture below.
blues90
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September 10th, 2018 10:00
Yes , I said I was confused. Not by the reason why I need this adapter but why I would need a 750 watt PSU and the one you listed IS the one I need .
Since this 780 OptiPlex MT came with a 255 watt Dell PSU wouldn't a decent 450 watt PSU be more than enough ? I was thinking the 450 watt CX corsair would be more than enough since the combined 5V and 3.3V on the dell 255 watt is 80 watt max the corsair 450 CX modular provides 110 watt . Plus is has all the safety features over voltage , under voltage ,internal short and all the rest , I forget what they all are . It has the same protection as the model and brand you suggested.
I just use this tower for watching videos and movies and email and regular forums and search engines. I don't do gaming or anything like that. The corsair is semi modular and seems to have enough Sata connections .. This tower just has the hard drive and DVD /RW . The only thing I don't care for is the length of the 24 pin and 4 pin cable which is quite a bit longer than the Dell PSU . This seems to be true of all the brands of PSU's that are semi modular.
speedstep
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September 10th, 2018 10:00
Dell power supplies have 140W or more combined on the 3.3v / 5v rails.
On larger Dell supplies this power GOES UP not Down. Its 225W combined for the Dell 875W unit used in systems Like the Aurora and Precision workstation. The CPU uses the 12v rail as well as other parts in the system. The PCI Bus uses the 3.3v/5v rails and 12v Rails for the video card. Power supplies do not operate in a Vaccuum using only watts only 1 rail only where you want it to go.
The other way to say this is YOU CANNOT USE 100 PERCENT POWER ON EVERY RAIL ON EVERY VOLTAGE. If you could then your power supply provides more than the rated output. 25 AMPS at 5v is 125W
25 AMPS @ 3.3v is 82.5W Note on the EVGA they show 20A 20A 20A 20A thats 80 AMPS on 12v which is 960W but combined they list 61A which is 732W. You cant be using 150W on the 3.3v rails and 732W on the 12v rails that would be 882W.
That is the reason WHY a specific EVGA 750 B1 works and a BQ B2 G2 does not. Power supplies are not a single spec of Watts with a single rail of 12v only. The other rails ARE USED and ARE Required. Feel free to use anything you want but when it does not work You will figure out what I am saying.
EVGA 750G1
blues90
22 Posts
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September 10th, 2018 14:00
speedstep: I get what you are saying . Yet my dell OptiPlex 780 mt has a Dell 255 watt PSU . P/N L255EM-OO .
+12VA 13A max +5V& 3.3V 80 watt max
+12VB 7 A max Peak +12VA out current 14 A
peak + 12VB 8 A
+5V 15A max =12VA & + 12VB max 220 W
+3.3V 8 A max
-12V 0.5A max
+5V (fp) 4 A max
I realize different part use different voltages . Yet with this PSU it works just fine. That's why I don't feel I need a high powered PSU just one that has more safety features.