Ok so i have a power supply with cross loading issues. The reason is because the 5.1v rail and 3.3v is not being used. So i need to find something that will allow me to drain some of there power.

So heres the issue
my 5.1v rail has 18 amps. 5.1*18=91.8W

So i need a resistor that can use about half the load of the 5.1v rail.

91.8/2= 45.9W

So basically what is the equivalent to a 45.9W of resistance in ohms?

Watts = Voltage X Current, W = V x I

Voltage = Current X Resistance, V = I x R

Current = Voltage / Resistance, I = V / R

Resistance = Voltage / Current, R = V / I

therefore:

R = 5.1 / 9 = .5667 ohms, rated at least 50 Watts

This Resistor may be hard to find and will be rather large in size, (big white rectangular).

Alternative solution:
(2) 1 ohms resistors connected in parrallel will produce a .5 ohm resistor.

I = V / R, 10.2 = 5.1 / .5 Ohm
W = I x V, 52.02 = 10.2 x 5.1

These Resistors may be hard to find and will be rather large in size, (big white rectangular).
They should also be rated at at least 50 Watts, maybe 100.

Good luck.
It may be easier to get another PS.
I just ordered this one, http://www.newegg.com/Product/Product.a ... 6817170017 for an older MB.

american wrote:I need help calcuating ohms

You need help with your spelling/typing, too.

Derring wrote:Watts = Voltage X Current, W = V x I

Voltage = Current X Resistance, V = I x R

Current = Voltage / Resistance, I = V / R

Resistance = Voltage / Current, R = V / I

therefore:

R = 5.1 / 9 = .5667 ohms, rated at least 50 Watts

This Resistor may be hard to find and will be rather large in size, (big white rectangular).

Alternative solution:
(2) 1 ohms resistors connected in parrallel will produce a .5 ohm resistor.

I = V / R, 10.2 = 5.1 / .5 Ohm
W = I x V, 52.02 = 10.2 x 5.1

These Resistors may be hard to find and will be rather large in size, (big white rectangular).
They should also be rated at at least 50 Watts, maybe 100.

Good luck.
It may be easier to get another PS.
I just ordered this one, http://www.newegg.com/Product/Product.a ... 6817170017 for an older MB.

Cant i just get multiple weaker resistors?

And BTW what are you planning to power with that PSU?

american wrote: Cant i just get multiple weaker resistors?

And BTW what are you planning to power with that PSU?

It will be hard to find 1 ohm resistors, not much use for them. I can't recall seeing them except maybe in a college electronics lab.
Or do you mean less Wattage? Most descrete electronic components are rated by Voltage (Capacitors) or Wattage (Resistors) so lowwer voltage or wattage are Weaker(?). And NO weaker is a no go. Do the math. To generate the power drop (45W) across 5.1 volts requires high current flow 9 amps, through very low resistance ( .5 ohms). 9 amps can kill, or zap the F'ing crap out of you.

PSU is for a Tyan S2460 'Tiger' MB, Dual AMD Athlon S462 ATX, 1.9GHz CPUs, AGP graphics. An Antec 500W failed for no apparent reason (shut it down 1 day, a couple weeks later I turned it ON and no go), I replaced it with a BFG 800w ( I had ) but this one is way over powered for requirements ( + it's a $100 PSU vs a $30 PSU). I'll return the BFG to my spare parts.

Thought: this is twice the speed of the 'pizza box'. But it has a problem with 'direct draw'. I think it is the MB BIOS (very old) but may be the ATI AGP GC or a combination of the two.

P.S.
Direct draw is a dog, it will not 'roll back' to a previous version, so be careful before you 'update'.

Derring wrote:

american wrote: Cant i just get multiple weaker resistors?

And BTW what are you planning to power with that PSU?

It will be hard to find 1 ohm resistors, not much use for them. I can't recall seeing them except maybe in a college electronics lab.
Or do you mean less Wattage? Most descrete electronic components are rated by Voltage (Capacitors) or Wattage (Resistors) so lowwer voltage or wattage are Weaker(?). And NO weaker is a no go. Do the math. To generate the power drop (45W) across 5.1 volts requires high current flow 9 amps, through very low resistance ( .5 ohms). 9 amps can kill, or zap the F'ing crap out of you.

PSU is for a Tyan S2460 'Tiger' MB, Dual AMD Athlon S462 ATX, 1.9GHz CPUs, AGP graphics. An Antec 500W failed for no apparent reason (shut it down 1 day, a couple weeks later I turned it ON and no go), I replaced it with a BFG 800w ( I had ) but this one is way over powered for requirements ( + it's a $100 PSU vs a $30 PSU). I'll return the BFG to my spare parts.

Thought: this is twice the speed of the 'pizza box'. But it has a problem with 'direct draw'. I think it is the MB BIOS (very old) but may be the ATI AGP GC or a combination of the two.

P.S.
Direct draw is a dog, it will not 'roll back' to a previous version, so be careful before you 'update'.

Ahh that sucks for me.. yea 18 amps is quite a zap aint it..

to think i have been working on live PSU. Good thing i tired my very best to not make contact...

So any other method i can take. is there any PS hardware that uses the 5.1v rail alot...

The reason why i asked is because logistic isn't exactly a quality brand PSu and is know for over rateing

1.9 GHX cpus. ~50 w each?
100W+50 for mobo and HD etc. +20 just in case.

170W. That PSU will still do the job.

BTW did i show you guys
[BEFORE]


[AFTER]


[PCI-e connectors ONLY 2x8pin 2x6pin] (Photo was taken while i was working on it)

Its my PC



AMD PhenII Quad @ 3.4 or AMD PhenII Dual @ 3.8
2x GTX 260's SLI (Havent tried OCing yet) [Bridge is missing i pic i know]
3x 7200 RPM sea gate HD RAID 0
Sigma 585W + Delta 575W
Tuniq Tower 120 (CPU cooling)
Xclio Godspeed Advance one (Case)
OCZ Freeze (Getting Shin-Estu [Shins the best out now])


Im proud of her again

Are you using both PSU? One for MB, etc. and one for Graphics Cards?
Make sure that both PSUs are gounded to the Case, or you could create a ground loop between the two PSUs ( a small current flow between the PSUs' ground (black wires) ).

I really don't understand your question.
Cross loading?
Are you saying that because you are not applying a load on the 5.1 and 3.3 volt connections of the PSU that the PCI-E power is not correct?

The HD and CD, use (red) +5 Volt, (yellow) +12 Volt and the Orange on the SATA is probably -12 Volt.

Derring wrote:Are you using both PSU? One for MB, etc. and one for Graphics Cards?
Make sure that both PSUs are gounded to the Case, or you could create a ground loop between the two PSUs ( a small current flow between the PSUs' ground (black wires) ).

I really don't understand your question.
Cross loading?
Are you saying that because you are not applying a load on the 5.1 and 3.3 volt connections of the PSU that the PCI-E power is not correct?

The HD and CD, use (red) +5 Volt, (yellow) +12 Volt and the Orange on the SATA is probably -12 Volt.

Yes and no. My 12v is giving me 12.25. 12.6 is the maximum tolerated by any ATX device. Under load a PSU has more trouble managing it voltage. And if any thing fails it can give a lethal dosage. The PSU almost expects that the 5.1v rail will be loaded. (This is because the Mobo primarily uses this). And there is no way i can test my PSU under load so i dont want to take chances with my 2x GTX 260's

The Orange wire on the SATA connector is 3.3V. How ever most devices only use the 12v and 5.1v. This is because if you have a Molex to Sata converter it doesn't have the 3.1v on it. THere for it would cause issue for people who dont have enought or any SATA connectors.

All of your Specifications will be X +- %, e.g. 12V +- 10%, so a measured 10.8 V under load would be within spec, @ no load the measured voltage maybe 12V.
Yes. Power supplies are designed to provided the specified voltages, currents, and power within specifications over varing specified load conditions.
Suggestion:
Forget the 'rigging' work around.
Get a PSU that will exceed the specifications of your needs. And sell the 2 PSUs to others where the specifications of the units will fulfill their needs.

Start thinking about paying yourself for the time you put into a project. @ $10 /hour the cost adds up. 8 hours = $80. This amount can be put toward the cost of the PSU. Solve your problems in a cost effective manner. In general, it is not the case that people are 'stupid or lazy', it is the case that it is more cost effective to pay another person to perform a more efficient solution. I will ask a neighbor auto mechanic a question and have a solution within minutes, where it would takes hours for me to research.
If you have a need for 'Memorabilia' talk to Tiger, need a 'Surveyor' talk to Space, 'Graphics Design' talk to BigFred, etc. This is what is called an economy.

I tried selling the two Pwr supplies. With no luck. Unfortunately the Delta Pwr supply is pretty old and doesn't fit a ATX case. The sigma is a OEM of a company called HEC. HEC is one of the worst pwr supply makers out there.

EVen if i could sell them (Maybe $40) i would still need more to afford a decent ~600W power supply. And yet that would leave me No room for any upgrades.

Being jobs less living with my parents doesn't help either.

Thats why my pay looks more like what people make in sweat shops. $.75 A day

All i did was use the time i wouldn't normally use for gamin to work on the rigging. Just to get enough money to do it i sold some stuff i had.