[My experiments and results so far]

Hi,
 At my place heat and dust are a major issue, and so I decided to move all of my open air rigs in to server case like structures. When I look at the current design, the fans are placed like this

    EXIT
   ^   ^
   |     |
| G | G |
| P  | P |
| U  | U|

  ^    ^
   |      |
FAN FAN
  INTAKE

But the gpu has such a design that I believe this setup may not be efficient in reducing the temperature. Because of all the plastic that is covering the sides, and the 3 fans doesn't seem to move much air around. This is the GPU I am talking about.
 
https://www.newegg.com/Product/Product.aspx?Item=N82E16814125953&cm_re=1080ti-_-14-125-953-_-Product

In my case average temperature is around 35C during the daytime and when I set the fans at 80% and power at 230w the temperature is still above 70C but when I place a 120mm 60CFM fan in front of the GPU like below

F G
A P
N U

temperature drops to around 60C even when I drop the GPU fan speed to 50% and leave the power at 230W. This made me conclude that those fans are not efficient in move much air around.

My experiments and results so far.

Setup : Fan at front

Initial Setup:

F G  F G  F G F G  F G  F G
A P  A P  A P A P  A P  A P
N U N U N U N U N U N U

Pros : This setup appears to be the best at reducing the temperate.

Cons: Each GPU has to be shielded from the next to prevent the exhaust of one getting sucked into the next as intake, This setup occupies more space.

Modified Setup:

F G |  F G  | F G |  F G  | F G |  F G  |
A P |  A P  | A P |  A P  | A P |  A P  |
N U|  N U  | N U|  N U | N U|  N U  |

Note: The shield has to be at-least .5 time more than the height of GPU to prevent the air from overflowing

Test results:

Option	No external fan |	Initial Setup |	Modified Setup |
Fan Speed	80%	70%	50%
Temperature	75	70 overall/Fist GPU at 60 |	60 overall
Power	230	230	230
Outside Temperature |	35	35	35

Setup : Fan at side

Setup:
    EXIT
   ^   ^
   |     |
| G | G |
| P  | P |
| U  | U|

  ^    ^
   |      |
FAN FAN
  INTAKE

Pros: No need for shield between GPUs, Don't take much space

Cons : No reduction in temperature maybe I have 60CFM fans? I am waiting for the 200CFM one's

Test results:

Option	Setup
Fan Speed	80%
Temperature	75 overall
Power	230
Outside Temperature	35

Setup Currently Testing: Fan at Side but Cross GPU

Setup:

| G       | G       |
| ^ P    | ^ P    |
|  | ^ U |  | ^ U |
   |  |   ^  |  |   ^ 
   |  |    |   |  |    |
  F  A  N  F  A  N

In this setup the GPU instead of being straight it will be at an angle that will cove the fan from side to side. For this testing I ordered some 140MM 200CFM fans, and will post the results once I get hold of them.

In the meantime I request anyone who has any idea to please share it here.

Thank you for your time 

Regards,
BLife

Hi,
 I recently ran into a situation that required to use 2 PSU in my mining rig and when the paper click trick is nice, every time I wanted to shutdown/restart the system I have to turn off/restart the second PSU manually and came across add2psu and found that to be costly so I went dumpster diving and got this solution.

Components you need.

1 Relay - SC5-S-DC-12V
1/4m  of different color Wires
2 Molex male pins
2 PCIE male pins
if you cant get the molex and PCIE pins you can use solder to solder the threads of the wire to make it single core.
4 heat shrink tubing.

The function of the relay is to connect the other circuit when the main circuit is powered up, and the connection is as follows

Connection Setup Red line indicate power flow

As you can see this relay can be powered from the first PSU that is controlled by the Motherboard and the secondary PSU can be connected to the secondary circuit of this relay to at as a switch.

Relay SC5-S-DC-12v This relay operates on 12v dc and I salvaged it from old UPS

Relay Backside It has 5 pin, 2 pins for input and 3 pins for output.

Connection of Wires Yellow & Black  wire brings in 12v from Molex and read wire and another black wire connects the pins 15 & 16 of motherboard cable.

Molex Connection Plug the yellow wire into the 12v and black into the neutral line

Motherboard Connection You can plug anyone in any slot it doesn't matter, all it matters is pins 15 & 16 must be connected.

Thats all to it, you can get a even low power relay to operate on 5v but I didn't have it.

Hope this is of some use to someone. If you have any doubts let me know.

Regards,
BLife

[Please Note]

Hi,
 If anyone is interested in customs cables for their rigs, I would be more than glad to make it. Details Below.

Details

Type              : PCIE
Connections : 6Pin to 6Pin, 8Pin to 8Pin
Cable Used   : 1.5 Sq mm Havells Wire

Type              : Molex
Connections : 4 Pin (You need to tell me your PSU Make and Model as each has a different Pinout)
Cable Used   : 1.5 Sq mm Havells Wire

Type              : Dupont
Connections : 2 Pin with On/Off Switch and Red or Green or White or Blue LED
Cable Used   : Rainbow Cables

Type              : Ethernet
Connection   : Cat 5, Cat 5E, Cat 6
Note             : If you are planning on Power over Ethernet please let me know in advance.

Cost Calculation : Total Cost = Pin Cost + Connector Cost + Wire Length + Shipping

Rough Estimation for 80Cm 6 PIn to 6 Pin PCIE Cable : 20 Rs + Shipping

So if you need any cables please let me know of the length of the wire, I will give you the final price.

Some Photos for Details

Engineers PAD-01 Crimper Used for Molex, PCIE, Dupont, etc

Sample PCIE Crimp

Another Sample PCIE Crimp

Sample 6Pin to 6Pin PCIE Cable

6 Pin PCIE Connector

4 Pin Molex Sample

Please Note As I use 1.5 Sq MM wire the maximum power that can be handled is around 250W but I strongly urge you to limit it to <225W for fire safety reasons. I can use 2.5 Sq mm wire but the PCIE connector wont be able to handle that many Amps.

Also Note I will never do double crimping, I will always split them using a Y joint with solder and wrapped it with heat shrink. Like This

Please post or PM if you need any cables.

Kind Regards,
BLife

Hi,
 I have nVidia GTX 750 Ti(2 GB) available for sale. Please see the details below.

Details

Months in Use       : around 5
Quantity for Sale   : 12
Model                    : nVidia GTX 750 Ti (2GB)
Place of Purchase : Chennai
In Warranty            : Yes
Asking Price          : Up for negotiation
Reason for Sale     : Moved to GTX 1080 Ti


Pictures of GPU

Rig Setup Before Dismantling

Entire Original Package

GPU Font Side

GPU Back Side

GPU Side Section

GPU Fan Area

Power Setup for the Rig

Hashrate for Mining ZEC on nicehash

I ran them with a TDP of 30W and they produced around 420H/s ~70H/s/GPU for ZEC(no over clocking), For XMR they produce around 280H/s for 35W with a over clocking of +170 Core and +650 Memory.

If anyone is interested please PM me or post here in this tread. As a new member I will be using Escrow, if within travel distance a in-person deal can be made.

Kind Regards,
BLife