TX750 dying?

I posted in another thread originally, but decided to create a thread of my own.

Original details I posted are:

new TX750 owner with the exact same issue as the OP described, started happening about 30 days after using it without issue.

 

After tearing apart my GTX260 SLI setup and rebuilding it into an 800D with a TX950 and an HD5870, I decided to buy a TX750 and put another system together out of older upgrade parts as a dedicate F@H box.

 

Win7 x64 Pro

Corsair TX750

Asus A8R-MVP / AMD 3200+ CPU

2GB RAM

eVGA GTX260 Core 216

640 GB Western Digital HD (SATA)

LG DVD Burner

 

The pattern I have now is... (1) successful paper-clip test, (2) successful OS load, (3) system powers off, (4) power button does nothing, (5) paper-clip test fails, (6) curse the system and leave it for a day or three until the desire to test if the PSU can catch a hammer dies down, (7) return to step 1.

 

Around April 13th was my first power off... I'm thinking 3 people with the same issue in the first half of April is a little too coincidental. There are also way too many reviews of screws working there way out of many Corsair PSU's to not consider it a plausible option.

 

If the PSU refuses to start on a paper-clip test after a "failure"/power-off... is that an indication that the PSU secretly likes the taste of hammers, that this PSU is failing, or that its protection mechanisms (working properly or not) have put it into a "time-out" state?

Extra info I have today is:

Looking back into my manual, the Asus A8R-MVP states a recommendation to "use a power supply unit (PSU) that complies with the ATX 12 V Specification 2.0 (or later version) and provides a minimum power of 400W""

According to Wikipedia

ATX12V 2.x PSUs have power distribution designed for late P4/XP PCs and for Athlon 64 and Core Duo PCs. They can be used with earlier P4/XP PCs, but the power distribution will be significantly suboptimal, so a more powerful ATX12V 2.0 PSU should be used to compensate for that discrepancy. ATX12V 2.x PSUs can also be used with pre-P4/XP systems, but the power distribution will be greatly suboptimal (12 V rails will be mostly unused, while the 3.3 V/5 V rails will be overloaded), so this is not recommended.

The same wiki also stated that:

ATX12V v2.01

 

This is a minor revision from June 2004. An errant reference for the -5V rail was removed. Other minor changes were introduced.

This lead to interesting research about cross loading (12V heavy vs. 5/3.3 V heavy).

Severe cross loading problems can cause a PSU to turn off when the load changes

According to Corsairs site, the TX Series is...

Supports ATX12V v2.2 standard and older ATX12V 2.01 spec

The mobo manual says ATX 12 V Specification 2.0 (or later version)... the PSU supports ATX12V 2.01... 2.01 is certainly later than 2.0... and 2.01 according to the wiki was a minor "reference update" to 2.0... so basically the same spec.

From what I can piece together (and understand), my A8R-MVP mobo and TX750 PSU are compatible... 12V "heavy". The system even ran well for 30 days after putting it together before troubles started. But the "symptoms" today seem eerily similar to cross-loading.

The system mostly refuses to turn on these days, but when it does it runs for a bit beofre shutting down. A test I have done was to remove the GTX 260 GPU and put on an older nVidia 7200 card from Gigabyte. This did not improve things.

But what it did allow was for me to reduce my "system power requirements" to the point I could slap in an old Enermax 360W PSU. With his PSU connected, I can turn the system on/off at will, like one would expect.

Is this enough of a test to prove the TX750 PSU is at fault? If so, and I go through the RMA process, what guarantee will I get the next unit will work "normally"? I am leery about paying shipping/reshipping; and doubly leery about entering a pattern of paying it more than once. NCIX has a nice Seasonic 620W for $75... doesn't take much shipping to approach that number. Or does the Corsair warranty cover shipping the dead/dying units back?

Also, is it possible to treat an RMA like an upgrade? Can I pay more to get a TX950 as a replacement? I've had good experience with my TX950 so far, and would rather have another TX950 based on my experience with the two units.

Did an interesting followup test...

Took the motherboard out of storage that was in the case previously...

Ubuntu Linux

Corsair TX750

DFI Lanparty

1GB RAM

ATI 9500 Pro (AGP)

2X WD 250GB

The system turned on 1st try, but the mobo howled... set my KVM to the right system and saw the note that I'd missed connecting the power to the GPU... 3.5" floppy tiny connector... easily missed/forgotten. What was "hopeful" about this was that previous to connecting this power cable, I could turn the system/PSU on/off at will and it would turn on every time.

I connected the last power connection and fired it up. Watched the Linux boot load screens, and it prompted for a reboot (something about the drives, which i half expected since the CMOS settings were lost as BIOS defaults were reloaded). After the reboot, nothing... pressing the power button... nothing... toggle the PSU switch and retry... nothing... reconnect the power cable and retry... nothing

Once again, it looks like the PSU can have moments of life after some rest, but just can't sustain it.

A fine enough second test?