900D Build Log - Green and Black watercooled.

[alpenwasser]

Ahh, okay. Maybe the 12v or 5v cancels one out, so 12-5=7, or 5-12= -7? Like I said I don't know much, so I'll take your word on it lol.

Heh, yeah it definitely is that. I have no idea how it works either tbh though.

If I may ramble a bit...

The PSU in a computer is a Voltage Source (as opposed to a Current Source).
What that means is that you basically specify it to put out certain levels of
electrical potentials on certain wires. If you then apply a load to said wire
(meaning you connect the wire to ground with a resistor between), the PSU
will send enough current through that wire to keep the potential on the first
wire at the specified level (that's basically how voltage regulation works, in
very rough terms).

The power dissipated in that resistor (in this case, the fan(s)), is then equal
to (DC calculation, AC is trickier):

P=U*I (P: Power, U: potential drop aka voltage, I: current)
with U=R*I, I=U/R we get
P=U^2/R=R*I^2

The term potential drop is actually very important, since voltage is
in actuality a drop from a higher electrical potential to a lower one (I'm taking
this terminology from German, my native tongue, if this is incorrect in English,
someone correct please).

Usually, the voltage for running a fan is 12 V (from the 12 V line to ground).
The power pulled by the fan is then

P=144 V^2/R, where R: Ohm resistance of fan

However, there's no rule that says you have to connect the high voltage wire
(12 V in this case) directly to ground, you can also connect it to 5 V, as mentioned.

So, the power pulled by the fan then becomes

P=(12 V - 5 V)^2/R=49 V^2/R

which translates into lower rpm's.

The thing that matters to the fan is only the voltage drop between the two
wires it is connected to. If the higher wire is on 12 V and the lower one on 5V,
the fan will behave as if the higher were 7 V and the lower one ground. There's
no way for it to tell the difference between the two scenarios, it will only care
about the drop (so, you would get the same result with 21 V on the incoming
wire and 14 V on the outgoing one, for example).

I hope this is somewhat understandable, also feel free to point out any
mistakes or things that aren't clear; it's been a while since I've done some
proper electrical calculations :lol:

 

[GregPalos]

If I may ramble a bit...

The PSU in a computer is a Voltage Source (as opposed to a Current Source).
What that means is that you basically specify it to put out certain levels of
electrical potentials on certain wires. If you then apply a load to said wire
(meaning you connect the wire to ground with a resistor between), the PSU
will send enough current through that wire to keep the potential on the first
wire at the specified level (that's basically how voltage regulation works, in
very rough terms).

The power dissipated in that resistor (in this case, the fan(s)), is then equal
to (DC calculation, AC is trickier):

P=U*I (P: Power, U: potential drop aka voltage, I: current)
with U=R*I, I=U/R we get
P=U^2/R=R*I^2

The term potential drop is actually very important, since voltage is
in actuality a drop from a higher electrical potential to a lower one (I'm taking
this terminology from German, my native tongue, if this is incorrect in English,
someone correct please).

Usually, the voltage for running a fan is 12 V (from the 12 V line to ground).
The power pulled by the fan is then

P=144 V^2/R, where R: Ohm resistance of fan

However, there's no rule that says you have to connect the high voltage wire
(12 V in this case) directly to ground, you can also connect it to 5 V, as mentioned.

So, the power pulled by the fan then becomes

P=(12 V - 5 V)^2/R=49 V^2/R

which translates into lower rpm's.

The thing that matters to the fan is only the voltage drop between the two
wires it is connected to. If the higher wire is on 12 V and the lower one on 5V,
the fan will behave as if the higher were 7 V and the lower one ground. There's
no way for it to tell the difference between the two scenarios, it will only care
about the drop (so, you would get the same result with 21 V on the incoming
wire and 14 V on the outgoing one, for example).

I hope this is somewhat understandable, also feel free to point out any
mistakes or things that aren't clear; it's been a while since I've done some
proper electrical calculations :lol:

My. God. Thanks dude

 

[alpenwasser]

My. God. Thanks dude

Happy to help

After all, what's the point of all that education if I can't put it to good use from
time to time?

 

[GregPalos]

New question (loop)

If anyone could help me by telling me how many they think I will need of 90 Degrees 45 Degrees and Barbs and how the best way of doing my loop would be, I would be so grateful! Keep in mind its in a 900D and this is the layout! The other images detail what Pump I have, what top (I'm not quite sure which is the in and outlet at the minute but it also has to be drilled in and the pump top only has the screw holes on one side) , what gpu block and what cpu Block. Keep in mind i'd also like some help on how I would maybe empty the loop? THANK YOU GUYS

 

[JordRiach]

looking good

 

[airdeano]

If anyone could help me by telling me how many they think I will need of 90°, 45°, and Barbs and how the best way of doing my loop would be, I would be so grateful!

that'd be an "in the case" determination of what is needed in fittings.

 

[GregPalos]

that'd be an "in the case" determination of what is needed in fittings.

sorry what?

 

[airdeano]

you'd need to have the assembly in the case, to find out how many different angle
fittings you'll need. and at a hefty price they can run up a pretty good tab.
and since the case isn't released yet... you'll have to wait for that

 

[pcjunkie429]

sorry what?

I think he means that it'd be easier to determine how many/which fittings/barbs you need by mounting the stuff in the case first because it'd be easier to see what the loop would look like.

-Edit-: Ninja'd h34r: <_<

 

[GregPalos]

I think he means that it'd be easier to determine how many/which fittings/barbs you need by mounting the stuff in the case first because it'd be easier to see what the loop would look like.

ah okay..

 

[GregPalos]

you'd need to have the assembly in the case, to find out how many different angle
fittings you'll need. and at a hefty price they can run up a pretty good tab.
and since the case isn't released yet... you'll have to wait for that

so fittings should be the last thing I buy? And out of interest then forgetting the fittings which direction should water flow round (more specifically the first image where I drew it out? Res -> Pump -> 480 -> up through gpu -> 360 -> CPU -> res?

 

[alpenwasser]

so fittings should be the last thing I buy? And out of interest then forgetting the fittings which direction should water flow round (more specifically the first image where I drew it out? Res -> Pump -> 480 -> up through gpu -> 360 -> CPU -> res?

Not necessarily the last, but it's usually one of the later purchases when I do
a W/C build. It's a lot easier to see how to best lay the loop when everything
is in the case before you, physically. At least it's that way for me.

As for the flow order, just make sure its "Res -> Pump", the rest doesn't really
matter I have found in the past few years of doing W/C.

EDIT: When I say "it doesn't really matter" what I mean is make it neat and tidy.
Performance is not affected by loop order, only having the pump before the res
is very inconvenient/stupid, the rest should just be laid out so that it looks best.

 

[GregPalos]

Not necessarily the last, but it's usually one of the later purchases when I do
a W/C build. It's a lot easier to see how to best lay the loop when everything
is in the case before you, physically. At least it's that way for me.

As for the flow order, just make sure its "Res -> Pump", the rest doesn't really
matter I have found in the past few years of doing W/C.

thanks you've been nothing but golden. And if you were a psu you'd be made of titanium *Facepalm* XD

 

[airdeano]

order isn't as critical (other than assuring pump has coolant full-time).
res->pump->480->GPU(s)->360->CPU->res
only reason to do the 360 before the CPU is a short run from CPU to res and avoid
long drooping line from 360 to res.
but it is all mute, until it is in the case.

 

[GregPalos]

order isn't as critical (other than assuring pump has coolant full-time).
res->pump->480->GPU(s)->360->CPU->res
only reason to do the 360 before the CPU is a short run from CPU to res and avoid
long drooping line from 360 to res.
but it is all mute, until it is in the case.

Once it's in the case I'll make sure to message you

 

[alpenwasser]

thanks you've been nothing but golden. And if you were a psu you'd be made of titanium *Facepalm* XD

That just might be the nicest thing anyone has ever said about me! :blush:

PS: I think it's totally awesome that 80plus picked Titanium as their next higher
efficiency rating. It's one of my favorite metals, along with copper (obviously )
and tungsten. Although awesome things can also be done with steel and alu.

EDIT: And bronze and brass, and magnesium. Dammit, I love metals, it's in my
genes (mechanical engineering)! :rock:

 

[GregPalos]

That just might be the nicest thing anyone has ever said about me! :blush:

PS: I think it's totally awesome that 80plus picked Titanium as their next higher
efficiency rating. It's one of my favorite metals, along with copper (obviously )
and tungsten. Although awesome things can also be done with steel and alu.

yeah but itll suck for americans don't their wall sockets only power 110w? apparently that causes problems for psu's with titanium?

 

[alpenwasser]

yeah but itll suck for americans don't their wall sockets only power 110w? apparently that causes problems for psu's with titanium?

According to Wikipedia there isn't even a
certification for titanium on 115 V. :headscratch:

 

[GregPalos]

According to Wikipedia there isn't even a
certification for titanium on 115 V. :headscratch:

yeah sorry i meant volts XD

 

[alpenwasser]

yeah sorry i meant volts XD

Haha, yeah I got that. It's sort of obvious in context :lol: The headscratcher
was more intended towards 80plus and the titanium rating not being available
on 115 V. I haven't done any further reading up on this so I'm not really sure
what the situation is in detail. I just quoted Wikipedia and was wondering if I
had understood the situation correctly