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1 Rookie
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2 Posts
1
12043
March 30th, 2020 11:00
Dell optiplex 790 case change
I have recently purchase myself a dell optiplex 790 sff i bough it with 16 gb ram i5-2500 core processor and 1tb hdd but the problem is i want to transform it into a gaming pc but theres not enough room for a new power supply and gpu my question is can I get a case cool looking or not that will take the parts and motherboard of a Dell Optiplex 790 small form factor?
speedstep
9 Legend
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47K Posts
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March 30th, 2020 13:00
No modern Dell uses ATX. 4 SLot MicroATX was explicitly designed to be backward 6 slot ATX. The mounting points of microATX motherboards are a subset of those used on full-size ATX boards. But Dell uses proprietary I/O and makes this part of the case instead of an I/O panel that comes out. Dell also does not always use ATX mounting points or power connectors. 790 thankfully uses standard 24 pin PFC EPS12v power supply. But thats where the compatability ends. The thermal sensor and front panel and USB connectors etc are proprietary as are the fan headers etc.
Dell swaps the wires around so that you will fry a dell fan on standard and the other way round. They have also switched to all the wires being black so you cannot tell what they are doing.
I did find this site that describes the work involved in "new" case.
http://www.pcdied.com/intel-magic/Dell/790/790.html
Fan header has 5 pins but only 4 wires are used.
Dell does not publish this. And some dells use standard wiring.
I believe this is correct.
YMMV
Dell MB
Pin Number
Function
Dell wire color
Std Fan
Pin Number
Std Fan wire color
Description
1
Sens (TACH)
White/Yellow
3
Green
Sens (TACH)
2
+12v
Red
2
Yellow
+12v
3
Gnd
Black
1
Black
Gnd
4
PWM
Blue
4
Blue
PWM
5
Key
unused
fireberd
9 Legend
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33.4K Posts
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March 30th, 2020 12:00
Possible but doubtful. Dell uses proprietary motherboards with non standard mounting holes, and proprietary and undocumented front panel connectors. Dell also uses proprietary case and CPU cooling fans that are monitored by the BIOS. If you feel you can overcome all this, go at it.
redxps630
9 Legend
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15.5K Posts
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March 30th, 2020 13:00
Agree. Optiplex 790 is the first series to use ATX motherboard (its immediate predecessor 780 was BTX). It is designed for business/corporation.
In addition to front panel ribbon cable and fan, 790 has a proprietary power switch header on motherboard separate from front panel (a “new” feature since older 780 etc. incorporates Pwr SW in the front panel).
You need to ask yourself whether taking this project the end result is worth the many troubles. The OEM board is a sandy bridge Q65 chipset that does not allow CPU OC on Dell BIOS. Do you want to move that business oriented engine into a cool sports car body, the two being incongruent?