Modding my Power Supply

[fonzie]

I bought my power supply: CORSAIR TX Series CMPSU-650TX 650W http://www.newegg.com/Product/Product.aspx?Item=N82E16817139005 in 2010 and it's been running nicely in my unRaid server since.  Because the PSU is not modular, it has a lot of cable that are simply cluttering my build.  I've decided that I want to mod the existing SATA power connectors and cut off the PSU cables that I do not need.  Here's a video explaining what I have in mind:

 

 

Since I have never modded a PSU before I am a bit concerned and want to make sure I have all my bases covered.

 

-can I simply cut off cables on the PSU that I do not need?

 

-how many SATA power connectors can I put on a single cable run on my PSU?

 

-any dangers I should be made aware of?

 

-any websites that could further aid in my endeavor?

[garycase]

Yes, you can cut any cables you are SURE you don't need [e.g. PCIe graphics power cables] ... although be SURE you don't need the additional cables for extra current capacity.

 

Since your TX650 has a single 12v rail, you don't need to worry about splitting the load among rails ... your only concern is the current capacity of the individual wires.    In general, each cable will have enough capacity for 6 modern drives ... but that really depends on the specific hard drives you're using and the wire gauge of the PSU wires.    Most PC power supplies use 18 or 20 gauge wire, although the higher-capacity units often use 16 gauge.  I'd guess -- but it's only a guess -- that a TX650 likely uses 18 gauge wire, so you're good for 20-24 amps of 12v current.

 

[fonzie]

ok, so I won't be adding more than 6 hard drives per cable run.  Yes, I believe the cables are 18 gauge.

 

If I were to cut some PSU cables and then later decide I want to use them, can I simply solder them back on and cover them with heat shrink tubing and be good to go?

 

although be SURE you don't need the additional cables for extra current capacity

 

what does this mean exactly? If I cut too many cables, will the remaining cables be receiving too much power? or are you just warning me not to cut off some cables that I may need in the future?

 

- Can I splice SATA Power cable into a "Y" shape with 2 SATA power connectors on the top on each side? I would be soldering the joint where it splits off.

 

                        Sata 1                  Sata 2

                          \                          /

                            \                        /

                            \                      /

                          Sata 3          Sata 4

                                \                /

                                \              /

                                  \          /

                                    \        /

                                    \      /

                                      \  /

                                        |

                                        |

                                        |

                                        |

                                      PSU

[garycase]

Not a good idea => the base of your "Y" will be carrying the full current for both legs.    So you need to consider the total number of drives that wire will be supporting.

 

What I meant about cutting unused cables is that, for example, a PCIe auxiliary connector has a couple of 12v lines and a couple of grounds.    These could easily be used to add a few more SATA connections if you simply added a 5v wire that you could splice into another line as close to the PSU end as reasonably possible.    This gives you another line with a direct internal connection in the PSU that can carry enough current for another 6 drives or so.

 

[Ford Prefect]

...the video shows a re-use of self-cutting/clipped connectors.

I'd stay away from that kind of mod.

If you want these type of connectors for powering a row of disks, I'd try and get these connector plugs brand new.

In fact I've seen the complete cables pre-build somewhere available ... monoprice, I think.

[garycase]

You can indeed get Molex => 4 SATA cables at Monoprice for under $2.00 each in quantity.

 

http://www.monoprice.com/products/product.asp?c_id=102&cp_id=10226&cs_id=1022604&p_id=8794&seq=1&format=1#largeimage

 

There are similar cables available (often for slightly less, but not by enough to matter) on e-bay.

 

Any of these are what the video shows disassembling and then re-using the connectors.  IF you can get the connectors released without breaking the locking tabs, there's nothing wrong with re-using them.    The advantage of the customized mods is that the connectors will be much closer together -- a nice advantage when all the drives are mounted close together.  It also allows you to have a much shorter run from the PSU [You're not connecting the power at the end of a run to the molex connection] ... which minimizes current loss in the cable.

 

[fonzie]

Not a good idea => the base of your "Y" will be carrying the full current for both legs.    So you need to consider the total number of drives that wire will be supporting.

 

The maximum amount of drives I will have on the "Y" cable would be 4.  Two on each side.  It's still less than the maximum of 6 so I thought it would be okay.

 

In fact I've seen the complete cables pre-build somewhere available

 

but buying the pre-built cables wouldn't solve my problem because I don't think I would find a cable the is specifically tailor-made for my case and has the exact spacing between my hard drives.

 

Yes, I'm planning on reusing the sata connectors, but they are in good condition.  I already took one apart and it doesn't look like it will lose connectivity if I reuse it.  I will be using new cables though.  I have an old PSU whose cables I will repurpose for my mod.

 

I have enough SATA power connectors on my PSU for all my drives, what I'm trying to do is just clear the clutter to improve airflow...hence the modding of cables.  I didn't have enough foresight to buy a modular power supply so now I'm doing this.  And like garycase said, the connectors will be much closer together and that's what I'm looking for.  I hate the loops that occur between the drive connectors on my current setup.

 

are the 3.3v cables needed on any hard drives at the moment?  I have a variety of different drives.

[Ford Prefect]

In fact I've seen the complete cables pre-build somewhere available

 

but buying the pre-built cables wouldn't solve my problem because I don't think I would find a cable the is specifically tailor-made for my case and has the exact spacing between my hard drives.

 

Yes, I'm planning on reusing the sata connectors, but they are in good condition.  I already took one apart and it doesn't look like it will lose connectivity if I reuse it.  I will be using new cables though.  I have an old PSU whose cables I will repurpose for my mod.

 

I have enough SATA power connectors on my PSU for all my drives, what I'm trying to do is just clear the clutter to improve airflow...hence the modding of cables.  I didn't have enough foresight to buy a modular power supply so now I'm doing this.  And like garycase said, the connectors will be much closer together and that's what I'm looking fore.  I hate the loops that occur between the drive connectors on my current setup.

 

Yes, I understand that use-case.

I am quite sure I've seen these cables with connectors spaced directly for a stack of drives.

If you WANT to reuse the connectors, do yourself a favor and re-solder the connection once the cable is fit.

These self-cutting-thingies are not the best solution in the first place, IMHO (you cannot tell how good the connection between blade and cable really is and there will be quite some current going through)

and re-using them is not going to improve them (the blades are not designed for that purpose and fitting these manually - normally this will be done with a tool/machine and a calculated force and speed/power - is another cause of failure.

[garycase]

As long as the total number of drives on your "Y" isn't higher than can be supported by one line, then your picture is fine.

 

I'm not aware of ANY current SATA drive that requires the 3.3v connection => I've used various 2TB, 3TB, and 4TB drives in recent builds, and often need to use at least one or two molex => SATA adapters, which never have the 3.3v connection.

 

[c3]

Re-using the IDC (insulation displacement connector) should be limited. But like the guy in the video if you take new parts and re-use once you should be OK. The bigger detail is using the correct wire size for the IDC. Wrong gage and you get a very poor connection, or break the connector. If the connectors are for 20 gage, use 20 gage and fewer connectors.

 

By soldering and shrink wrapping your build solid connections for the "Y" and any reconnections, so they will be fine.  But stay within the load range of the wire size.

 

There are no 3.3v requiring drives in that form factor.

 

I would make sure the length between the power supply and the first connector allows for working the cable through the case and on/off the first drive. Without a bit of wiggle, my fat hands sometimes have a hard time removing the cable.

[lionelhutz]

Cutting the wires off where they leave the power supply? Yuck! If you can solder, then open the supply and de-solder the extra wires from the circuit board. You can get new wire the right gauge for the connectors and add it back into the empty holes to make custom harnesses if necessary.

 

[fonzie]

Cutting the wires off where they leave the power supply? Yuck! If you can solder, then open the supply and de-solder the extra wires from the circuit board. You can get new wire the right gauge for the connectors and add it back into the empty holes to make custom harnesses if necessary.

 

I'm scared of opening the power supply because unless you really know what you're doing (I'm no electrician), you could cause serious injury.  I'd rather not take that risk.

[garycase]

If you're very careful when you open it, there's no real risk [you're certainly not going to do this with the unit plugged in  ].    The only "risk" is if you short something internally, so when it IS plugged in the PSU "goes up in smoke" !!

 

But if you take the cover off, you can probably see where the wires you want to cut are attached to the circuit board.  You could either cut them VERY close to the board; or de-solder them.  The risk of de-soldering is that you may loosen an adjacent connection for the same power bus -- so be VERY careful.

 

On the other hand, cutting the wires where they exit isn't really all that bad as long as you don't do it so close to the case that there's a risk of shorting.  The neatest way to do it externally is to cut them about 3/4" from the case, and put a tiny length of heat-shrink tubing over the stubs [electrical tape is an okay-but-not-as-neat substitute].

 

[lionelhutz]

I'm scared of opening the power supply because unless you really know what you're doing (I'm no electrician), you could cause serious injury.  I'd rather not take that risk.

 

Before doing anything, unplug it and press the power button to drain any remaining power. Then, disconnect it and disassemble it to remove the extra wires. Just pay attention that any screws and any insulation inside get back where it was. Take pictures if you need to as you go.