Adding extra Internal PSU in optical bay for graphics cards [Build log]

Figured I'd start my own thread. Will be updating with progress as I go along but I haven't had much time lately so it will probably be a while before I finish. The complete finish will be able to provide 4x 6pin and 2x 6+2pin PCI-e power cables, 2 of the 6pin are from the motherboard.

Added a E-Power EP-450CD 450w auxiliary power supply that mounts in the optical bay. This provides 2x 6pin PCI-e and 2x 6+2pin PCI-e. You will need a female PCIe power > female molex adapter which are cheap on ebay. I will be cutting mine down to save room for all the cables. To get the 115v power the PSU needs, I'm going to tap in the main plug the MP cable plugs into. This way I won't need to run the main power cable though the MP and out the PCI bay since it came with it's own PCI cover plate. I'm possibly going to be upgrade the internal PSU fans with more quieter ones. They are small so they are a little louder.

I will routing custom-made sleeved cables. I believe there's enough room to route them through the front of the motherboard and down in front of the PCI fan.

Had some spare time(taking a break off the house tonight) and did one of the 6 pins and routed it.

As mentioned, there isn't much room so I think I'll only be able to route 1 more cable unless I cut some of that top tray out. I had to label and route 1 wire at a time since space is limited and the connector won't fit through that small hole. That means I'll have to remove it to cut it. When I do, I need to remove the PSU anyways so I can route the main power cable and tap off the main power plug that plugs into the back of the MP.

There is a cover plate in the back that will needs to be removed. This is held on with 2 philips screws.

I will cut out quite a bit of the top plate so I can eventually route all 4 cables. Here's some pictures of the progress so far. I also cut my molex adapter since it was a 3 way and also to shorten it and soldered the ends and shrink tubed it. All my connections are soldered for reliability and better connections.

Here it is completed. I was able to run 24 wires through the slot near the front, which is 4x 6pins. There was not enough room to route sleeved cables which I initially tried to route. Everything works great. Running 2 670s of the aux PSU.

Click thumbnails to enlarge.





Here is the hole I drilled to run the power for the power supply. I plan to install a mini plug here so I can unplug the Mac if I ever need to move it.



I can convert 2 of the 6pins to 8 as soon as I figure out how these propritery cables work.

Reserved~

All Taken said:

Very nice write up dude, looking to do the same to run a 690. Trying to find that model or any 5.25" Power supply in the UK is impossible though.

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Thanks!
A 690 would be incredible on a Mac pro, especially under windows. Look it up tho but I remember hearing people couldn't get the second GPU working under windows but show up as 2 in OSX? Unless a newer driver came out since then? They are $1100 here in the States but this GPU would handle it with no problem.

slughead said:

How did you get the cable plugs through there? did you take off the back cover or something?

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Yes that back shield is removed, I have pictures above. It's held on with 2 screws. I just removed mine all together but I'm sure it could be put back in.

You do have to remove the pins from the pci connectors and route them one-by-one since there isn't enough room.

Dr. Stealth said:

Excellent write up..... You inspired me. $$$

I've been wanting to add another 4GB 680 to my MP and this was just the poke I needed to make the move.

I don't do any gaming, this is for cadd & rendering....

Just ordered a 450 Watt PSU:

http://www.newegg.com/Product/Product.aspx?Item=N82E16817104054

And a second EVGA GTX 680 FTW+ 4GB:

http://www.newegg.com/Product/Product.aspx?Item=N82E16814130794

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Awesome.

I modified 2 of the mini 6pin connectors off the motherboard into a single 8pin connector and used a dual 6pin to 8pin adapter and now I can power 2 GTX Titans all internally. Used the remaining 2 6pin PCIe connectors for other 2 slots. A Titan uses 2x 6pin and 2x 8pin. I'm sure that 2 780 Ti's will also be able to work no problem.

Temps have definitely gone up a notch now so I will be keeping my eye on that. Testing out folding and they both have been 100% stable the last 12+ hours.

Here's the ebay member and the orders I placed through him so you can gauge a price. I believe I had him make me 24" wires which are 16ga, 18ga is the minimum that is recommended I would have ran. I am in no way affiliated with him.

http://stores.ebay.com/Ensourced-Custom-Sleeved-Cables

QtyItemOptionsPrice2Black Custom Unsleeved 6 pin ATX PCI-E Extension Cable
Item # 271095684655 $10.56 USDAmount $10.56 USD

QtyItemOptionsPrice2Black Custom Unsleeved 8 pin ATX PCI-E Extension Cable
Item # 271095686203 $15.32 USDAmount $15.32 USD

They both work great even when overclocked to 1200mhz. The fans run fast though

HappyMac314 said:

Thank you for your replies and comments! So if I understand correctly, you earlier had your ePower PSU the same direction as mine (fan pointing towards the front of the Mac Pro) and it was loud. However, when you got the long cables and were able to orient the ePower PSU pointing the fan towards the back of the Mac Pro (same direction as main fan), the noise got better?

Also, nice setup in your pic! Dual SLI Titans must really fly!

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I always had the orientation from front to back. I never had to reverse the fans. It's quiet enough for me where I didn't have to replace the fans for something quieter.

riggles said:

Is there a reason why you chose to go custom length PCI-e cables instead of getting extension cables? It looks like you had to take that sleeving off anyway?

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I couldn't sleeve them as there wasn't enough room in that back corner to fish through 24 individual sleeved wires. I went with 24" or longer wires(can't remember exact length) since I didn't want to reverse the fans in the aux PSU to keep the airflow going front to back.

I bought my own roll of Sleeving and shrink tubing as I was going to do that myself and had some extra wire and connectors to make a couple sleeved cables, I'll keep them if I ever do a PC build. I just had a guy send me all 24 of the cut wire, connectors and pins and did it all myself.

riggles said:

Right, I want to keep the PSU oriented its intended way as well. Just having a hard time knowing whether it would be better to buy those custom length power cables or just thread the included cables thru and buy extension cables as needed to connect to the card(s).

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Those stock cables are huge! I doubt you'd get one cable fished through.

If anyone's interested, The ePower PSU is for sale on newegg.com for $24.99 and $3.99 shipping!

http://www.newegg.com/Product/Produ...17101044&cm_sp=&AID=10440897&PID=4549763&SID=

This is a great deal and I highly recommend it. I've put it through some extreme rigorous testing and running probably maxed out for days on end and still works great.