Dual PSUs and PCI-E GPUs: The Experiment

[K404]

Bought an el cheapo PSU from the bay and hooked it up to me trusty Tagan:

http://img156.imageshack.us/img156/8372/imag0001uc6.th.jpg (http://img156.imageshack.us/my.php?image=imag0001uc6.jpg)

http://img156.imageshack.us/img156/6240/imag0007sx2.th.jpg (http://img156.imageshack.us/my.php?image=imag0007sx2.jpg)

http://img156.imageshack.us/img156/6651/imag0002vx0.th.jpg (http://img156.imageshack.us/my.php?image=imag0002vx0.jpg)

So my primary PSU is powering....the mobo and CPU

My 2nd PSU is powering my opticals, HDDs, fans, pump and PCI-E plug. Might move some stuff back over to the primary.

Still to try 3D benching, but I expect no issues. The quality of the 2nd PSU is my only doubt, and thats not a problem for other users.

If anyone has any info/input on this or warnings that i`m sailing into trouble with PCI-E plug power regulation strain, please speak up.

This is only suitable for GPUs with their own onboard voltage regulation.

Kenny

[K404]

Please ignore this for now...My 2nd PSU stopped and might have taken my hard disks with it. Not sure why yet, but dont try this at home please!

K

[EsaT]

Please ignore this for now...My 2nd PSU stopped and might have taken my hard disks with it. Not sure why yet, but dont try this at home please!
That El cheapo propably doesn't have high efficiency and load requirements so just try starting it separately.
That should tell is it KIA.

Now if PSU takes HDs with it quality is propably such that it doesn't require any reason for dying.

[K404]

HDDs are still working...PSU was working but I went back and made sure it was dead...

Errr....with some help from JohnnyGuru..back to stage 1! Relay+ green/ black wires. I need better load balancing as well. Why do PSUs still have a 3.3V rail???

[nn_step]

if I remember correctly PCI/AGP and ram is powered by the 3.3v

[K404]

True, they are, but cant they use the 5V line instead, with some extra VRMs?

Or..go the other way...everything uses the 3.3 and 5V rails and we can ditch 12V rails..less heat from "wasted" voltage?

[Helmore]

Isn't DDR2 powered from the 5V line and DDR1 from the 3,3V line? Or does this just depend on what the mobo maker prefers to use?

[WeStSiDePLaYa]

Isn't DDR2 powered from the 5V line and DDR1 from the 3,3V line? Or does this just depend on what the mobo maker prefers to use?


i dont see why ddr2 would be powered from the 5v rail, its power draw is less than ddr1.

[jonnyGURU]

Yeah.. still 3.3V.

I wouldn't worry too much about 3.3V load, though. 3.3V is dropped down from the same rectifier as the 5V. I don't think the MOSFET that regulates the 3.3V needs a load on it.

[K404]

so I just need to worry about finding something for the 5V rail? Maybe this PSU really was just poor then. Will try and find another PSU, and get a relay for the PS_On

:)

[EsaT]

Or..go the other way...everything uses the 3.3 and 5V rails and we can ditch 12V rails..less heat from "wasted" voltage?And get hugely increased power transfer losses, it's current which causes transfer losses.
Remember
P=UI
P=IIR

[Helmore]

And get hugely increased power transfer losses, it's current which causes transfer losses.
Remember
P=UI
P=IIR
This is also the reason why they use a much higher voltage for the 'transport' of the electicity. (I mean those high voltage cables) It will make sure that there won't be such a major energie loss.

[bullet2urbrain]

This is also the reason why they use a much higher voltage for the 'transport' of the electicity. (I mean those high voltage cables) It will make sure that there won't be such a major energie loss.

much higher gauge of wire too tho, bigger wire == less resistance per meter, therefore less Voltage drop, and higher voltage to decrease the current...

but both are true.

[K404]

Thats true about electricity transfer across country, but the multiplication factors are so much bigger.

Either way....either the 3.3V or 12V rails can be removed from PSU spec, IMHO :)

Still gotta find an uber cheap SPU to try again with this :)

Kenny

[EsaT]

Either way....either the 3.3V or 12V rails can be removed from PSU spec, IMHO :)What? Do you want to have finger thick solid wires going inside case? :nono:

Even using 5V for transferring power instead of 12V would need five times bigger cross section area of wires just for keeping transfer losses at same level.
With 3.3V you would need wires with 13x cross section area!

[Helmore]

Even using 5V for transferring power instead of 12V would need five times bigger cross section area of wires just for keeping transfer losses at same level.
With 3.3V you would need wires with 13x cross section area!
Most people don't realize this, but this is one of the main reasons of why we now mostly use the 12V line. Google's servers even have 12V only PSUs that are customly designed for them just to provide the extra efficiency and less loss during the 'transfer' of electrical energy.

[INJViper]

Please ignore this for now...My 2nd PSU stopped and might have taken my hard disks with it. Not sure why yet, but dont try this at home please!



All I have to say is Ouch!

[K404]

The HDDs survived :)

Someone has to try this...its been discussed/argued over for long enough, and i`m game to try it...even if some of my views above are a bit wide of the mark :p: I still reckon we can drop the 3.3V rail though :p: