The MB does not appear to power up and the PS does not turn on

[Rags]

Problem: The MB does not appear to power up and the PS does not turn on.

Full specs:
ASRock 939SLI32-eSATA2 Socket 939 ULi M1697 ATX AMD Motherboard
AMD Athlon 64 3000+ Venice 2000MHz
OCZ 2GB (2 x 1GB) 184-Pin DDR SDRAM DDR 400 (PC 3200) Unbuffered Dual Channel
eVGA 256-P2-N437-LX Geforce 7300GS 256MB GDDR2 PCI Express x16
Seagate Barracuda 7200.9 ST3250824AS 250GB 7200 RPM SATA 3.0Gb/s

Ever Case E4252BB-53 Black Steel ATX Mid Tower
SeaSonic S12-500 ATX12V 500W Power Supply

Microsoft Windows XP Home With SP2 - OEM

NEC 16X DVD±R DVD Burner Black IDE/ATAPI Model ND-3550A
SONY Black 1.44MB 3.5" Internal Floppy Drive Windows
LINKSKEY LKA-CR15B 19-in-1 USB 2.0 Reader/Writer

DELL - UltraSharp 1907FP 19-inch Flat Panel LCD Monitor

Here are the steps I've done:

Bought a cheap PS tester [CompUSA ATX 12V Version 2.0 Power Tester] and everthing seems to check out. The Seasonic was so quiet, I had to use a light to see the fan blades moving.

Did the "out of the box partial build" with the PS, MB, CPU & fan, video card [in each PCI-16 slot], single stick of memory [tried both in multiple slots of both banks], shorted the pwr sw posts and did a connect through the switch.

The CPU fan did not come on. Tried the case fan powered from the MB - nothing. The only sound I get is a very faint sound out of the PS at the moment the pwr sw is shorted. It sounds faintly like either a small relay trying to close or a crackle. It will not happen on a second short. I either have to wait or short with the PS power off to reset the conditions.

I remember reading something about SeaSonic S-12's sometimes having a proble with too little load on the 5V rail but thought this was a problem during boot. I can't find the article again.

For an extra test, I used the PS to run by old Pentium2 (~1998) system and it seem to work OK although it took a couple pushes on the start button.

One more thing I though of at work was to pull the 62Meg memory out of the old system and try it when I get home tonight.

Any other tests or configurations, I can do to try & isolate & diagnose the problem?

BTW: This is my first build although I done a few upgrades.

Thanks for any help.
Rags

[blue60007]

I'm not totally sure about the quality of that brand motherboards...you wouldn't happen to have another on hand to test the other parts (or test those parts in that system)?

The RAM in the PII system will be too old to work in this new system.

[Rags]

Hi Blue60007,

I tried a ~2-year NEO480 with the MB and it seemed to post. Will be doing a more complete check tonight.

Meanwhile I found a discussion on SilentPCReview about a minimum load on the 12V rails of SeaSonic & some other high efficency PS's. I may try a resistor just to get the load up and see if that works.

Meanwhile I go the following back from SeaSonic tech service.

Dear Sir

As you said the unit works fine on another system. That means the PSU is not a fault.
The symptom you mentioned does not look like a min 12v load issue, which will let the fan turn for a while and then shut off. While this, raising more 12V load would overcome this in practice. And you can try if it works on your case.
However, the symptom that neither the PSU fan nor the CPU fan would turn on is more likely a +5vsb over load issue. This results from the +5vsb load of system is over and out of spec of the PSU. Please be informed that the S12-500 truly conforms to the newest Intel specifications and have been tested by Intel to be in conformity. Recommend you to ease the peripheral or contact our local RMA department to see if they can do further for you, thanks.

I'm not sure what the +5vsb is and how that differs from the regular 5V rail. I have noticed on the tester I used that it seemed to decay rather than just go off when I turned of the PS.

Anyone out there who would care to educate me on this - please reply.

Rags