How many Amps does a 486 PC use on +12V? \ VOGONS

How many Amps does a 486 PC use on +12V?

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First post, by GabrielKnight123

Posted on 2019-12-16, 06:33

GabrielKnight123 Offline

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How many amps does a 486 pc use roughly on +12V if using:

One IDE HDD
One DVD drive
A Pro Audio Spectrum 16
ISA MPU-IPC-T MIDI card
One 3 1/2 floppy drive
One PCI video card
Keyboard and mouse (serial)
2x 12V fans (1x case, 1x CPU)

I ask because I have an adapter for my 24 pin ATX power supply and I have removed the wires from the power supply I didnt need like PCIE and SATA but on the power supply it says the minimum on each rail is:

+3.3V = 1A
+5V = 1A
+12V1 = 0.5A
+12V2 = 0.5A
-12V = 0A
+5VSB = 0.1A

and since the +12V has two rails on my power supply and im not using the one from the PCIE should I just make the +12V from the molex cables go to the +12V rail that the 24 pin cable goes to or would that all together be over 18A on the +12V?
My 40GB hard drive uses 600mA so that covers the minimum for +12V1 but what do you guys think? Oh yeah the adapter im using makes -5V

https://drive.google.com/file/d/1JnQUOPHEukwa … iew?usp=sharing

Reply 1 of 6, by PD2JK

Posted on 2019-12-16, 08:09

PD2JK Offline

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Not sure, but the 3.3V from an ATX PSU is unused, when connecting a simple ATX-AT converter cable.

Question is how the PSU reacts on this in the long run... But you can use a power resistor on the 3.3v line to create some load.

i386 16 ⇒ i486 DX4 100 ⇒ Pentium MMX 200 ⇒ Athlon Orion 700 | TB 1000 ⇒ AthlonXP 1700+ ⇒ Opteron 165 ⇒ Dual Opteron 856

Reply 2 of 6, by GabrielKnight123

Posted on 2019-12-16, 08:50

GabrielKnight123 Offline

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The one I have has a 10 watt resistor on 3.3V to balance the load over the rails, it was recommended to me from someone here on Vogons, but going back to my power supply would it be fine to have the Molex 12V on a separate rail or should I put all 12V on one rail? Would all together reach 18A?

Reply 3 of 6, by bakemono

Posted on 2019-12-16, 14:29

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Would all together reach 18A?

On the 12V rail? I doubt it would even reach one third of that.

again another retro game on itch: https://90soft90.itch.io/shmup-salad

Reply 4 of 6, by maxtherabbit

Posted on 2019-12-16, 16:43

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Probably like 4

Reply 5 of 6, by pentiumspeed

Posted on 2019-12-16, 17:44

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In old days of computing, most attention is 5V and enough current on 12V up to 60W. Which is one voice coil type actuator full height hard drive (around 40W) for most 200W PSU with P8 and P9 type AT/baby AT style PSUs.

If you are running many 3.5" hard drives, that is less of a concern since they usually are not more than 12W each (both 5V and 12V watts) on each 3.5" drive.

Cheers,

Great Northern aka Canada.

Reply 6 of 6, by SirNickity

Posted on 2019-12-16, 22:59

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Is it common for a PSU to require a load on EACH rail like that? Most of the more modern ones start and seem to run indefinitely without any load, but even in recent history it seems all the ones I've ever used share a trafo core and regulate all the rails off either 5V or 12V.

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