Just looking for second-opinion experience-sharing before I flip the switch

[BonzaiDuck]

I'm replacing a 750W Seasonic modular "Gold" X-series PSU with a 650W Seasonic modular "Gold" X-series PSU.

The size is exactly the same, the markings are exactly the same, the orientation of the ports and fan direction/location are the same.

I thought to leave the wiring in place, assuming that the plugs and wires would all fit.

All of the six-pin peripheral SATA plugs fit snug but easily.

The 8-pin 12V motherboard plug fits the designated port easily.

I then noticed that the PCI-E plug on the old wire is a 12 or 16-pin plug for a PSU which only provides 8-pin ports. So that's replaced.

The main motherboard cable -- two plugs at the PSU end -- has the larger one with a latch which bends slightly sideways when pushed in. Bad sign.

Replacing the wire-harness with the new one, I realized that there were two additional pins at the end of the plug. So the recognition may have staved off disaster. Certainly the second and smaller plug connecting to the main ATX motherboard power socket fit, but it's all part of the same wire-harness. So that's solved, regardless.

As for the 8 pin and 6-pin wires, they all fit fine as I said, although I can't be sure the latch locks into place. But removing them seems to require pinching the latch-lever, so it may be "OK."

Anyone have an opinion about this before I close it, plug the AC and switch on? I'm rather surprised at the difference between two PSU's in the same quality and series classification. The old 750W is 5 and a half years old, and I just received the replacement 650 from the Egg. The 8-pin motherboard plug is very hard to reach. I don't want to remove the NH-D14 cooler. If I don't have to, I don't want to.

UPDATE: Just realized my custom exhaust duct was covering access to that 8-pin plug. Easy.

That leaves the SATA connections. I'm pretty sure that's all good with the old wiring.

 

[TennesseeTony]

Don't do it. I started off reading and saying to myself yeah sure, same brand. But when you got to the first difference, all sorts of flags were raised.

First off, all those connectors that DO fit, are a industry standard. What is not standard is the pinout. I ebayed a Seasonic 850W from a bitcoin miner. He had numerous PSU's for sale, and sent cords that looked the same, plugged in the same, etc, but were for a different brand. I only knew this after I lost 2 SSDs, Bluray drive, and a few fans, and other lesser components.

Seriously not worth the risk. Run your new wires, and keep the old ones clearly identified as belonging to the old PSU.

Now then, get that thing running and join TeamAnandtech in our fight against Tom's Hardware!! (see link in sig)

 

[BonzaiDuck]

Don't do it. I started off reading and saying to myself yeah sure, same brand. But when you got to the first difference, all sorts of flags were raised.

First off, all those connectors that DO fit, are a industry standard. What is not standard is the pinout. I ebayed a Seasonic 850W from a bitcoin miner. He had numerous PSU's for sale, and sent cords that looked the same, plugged in the same, etc, but were for a different brand. I only knew this after I lost 2 SSDs, Bluray drive, and a few fans, and other lesser components.

Seriously not worth the risk. Run your new wires, and keep the old ones clearly identified as belonging to the old PSU.

Now then, get that thing running and join TeamAnandtech in our fight against Tom's Hardware!! (see link in sig)

Since I pretty much deduced some important points you make since my last post, your "Tom's" notice has my attention. At this writing, I just replaced everything. Usually, I'd been able to identify 12V, 5V and ground wires and trace them to comfort myself. But it's only as much of a hurdle as the system's initial cable-routing. I'm more of a veteran at this than even I realize.

The 8-pin mobo ATX12V was so easy to replace, I'm surprised I saw opposite at first. I finally just pulled one 6-pin SATA wire at a time, picked the appropriate length and plugs, to then replace everything with what had been provided.

This might concern me again in the future, because under the same assumption of same brand and similar models, I've failed to mark any of my surplus cables in the parts locker for identification.

On the up side, one objective or constraint in my household IT optimization plan is to reduce the number of devices turned on at a given time, with an eye toward tempering cable-clutter.

If I want hot-swap bays, FP USB3 hub or FB eSATA, they have to fit into the equation from the time each machine is built.

But that's where I am now. To get there, this machine went through modest evolution. I'm glad I'd done it as well as I did.

 

[BonzaiDuck]

Now it appears that infant-mortality claimed the new PSU. Won't power on the system after initially two reboot cycles. Old PSU restores everything as it was.

Time to RMA. If interested, check my thread on "Motherboards," but this looks pretty cut and dried.