Building a New Computer - POST Revisited

I have been running on the new PC for some time and haven't encountered any problems. Here is the reason why I couldn't get the damn thing to Power On Self Test a few weeks ago:

The connector in the center of that picture is referred to as JATXPWR2 in the Biostar NF4UL-A9 manual. Other than a motherboard layout diagram on page 7, it is mentioned only once, tucked in Chapter 3 on page 13. Yes, it is the direction power connection for the CPU. Yes, the manual mentions this. No, I didn't read closely enough and I didn't have this plugged in. Kinda hard for a computer to operate without juice in the transistors.

But the chapter preceding Chapter 3 (helpfully titled "Hardware Installation") dealt with inserting the CPU, memory, external storage, and peripheral connectors. It reminds the user to connect the CPU fan lead to JCFAN1. Not the barest of hints was mentioned regarding a separate power connection to the CPU from the power supply. Furthermore, here's what the manual says on page 13:

3.2 DETAIL SETTINGS

ATX Power Source Connectors: JATXPWR1 and JATXPWR2

JATXPWR1: This connector allows user to connect 20-pin power connector on the ATX power supply.
JATXPWR2: By connecting this connector, it will provide +12V to CPU power circuit.

[table detailing the various pin assignments to each of the lines in the two power connectors]

That's it. No warning in the trouble shooting section about checking for JATXPWR2 if nothing happens when the system is powered on. Nothing in the section that was created to instruct the user to install hardware. The crucial aspect of this connector is almost shrugged off as an afterthought.

It was immediately obvious to the Fry's technician what was wrong because he's seen many modern systems. I, however, have never built one from the ground up and have missed several product cycles. I've never heard of a mainstream consumer motherboard requiring a dedicated power connection to the CPU. Shows how out of date I am, but c'mon this is an oversight and the manual ought to be rewritten to reflect how important this damn plug is.

Thankfully, the Fry's tech said he would waive the normal $70 fee for diagnosing my problem if he could find it in less than 15 minutes. It took him less than five.

*bangs head on wall*

The small things get me all the time. Though there is the chance that single stick of dual-channel Crucial RAM might have tripped me up anyway, I obsessed over it so much I neglected to just step back and double-check everything again and RTFM a little harder.

Previous posts:

• Building a New Computer - The Past, the Present, and the Parts
  
• Building a New Computer - The Antec Sonata II Case
  
• Building a New Computer - The Guts Are Here
  
• Building a New Computer - POST Problems
  
• Building a New Computer - Diagnosing My POST Problem
  
• Building a New Computer - Complete!

Posted by Drizzten at January 23, 2006 06:51 PM