Won't Boot unless CMOS button is pressed

[Supersonicwolfe]

Welp I have a old Shuttle system which I am trying to restore and use it as my "old games" machine (and maybe NAS server in future). But I ran into some weird booting issue...

System spec: Core 2 Quad 9550, Shuttle SG41J1 LGA 775 Mini-ITX motherboard, 2x DDR2-6400 G.Skill 1GB stick (going to upgrade to at last 2x 2GB), a small hard drive, brand new EVGA 600W power supply.

OS is WIn7 Ultimate 64 bit edition

 

In short, the thing won't boot unless the CMOS button is pressed.

 

Long version:

The issue is that it won't boot from a "cold start" (power off for a while), unless pressing the CMOS and the power button at same time. Then everything seems fine after loading the default boot options, all rams detected and at correct speed according to CPU-Z. 

The Interesting part is the machine boots fine during restart by windows or if I shut it down and try to restart the machine after USB powered down and fans stopped.

I wanted to flash the BIOS but unfortunately the BOIS from Shuttle's website won't work on 64 bit Windows 7 Ultimate. The current BOIS on the board is the latest available.

 

So what might be wrong and how to fix it??

I do know this machine probably sat in a closet without power and ram sticks in for a quite a while. it was likely a senior design project computer from the university...

I already got her a brand new 600W power supply and new CMOS battery... 

[AskTJ]

Are the power buttons plugged into the motherboard correctly?

 

That ram speed of 6400MHz seems a little fast.

[Supersonicwolfe]

23 hours ago, AskTJ said:

Are the power buttons plugged into the motherboard correctly?

 

That ram speed of 6400MHz seems a little fast.

It should be  PC2-6400 (DDR2-800MHZ)

 

Well I actually digged up manual to figure out the pin out of the power button and basically eliminated the power button issue. The machine won’t boot even if I short the switch. But it boots normally if I pressed the button (or short the power swirch pin) within 1-2 minute of the machine powered down... the machine will boot fine if I press the CMOS button (of course I need to reconfigure CMOS before loaded into Windows).

 

Matter of fact, I can hear the powersupply makes a little bit whine when I press the power button, which should means the power button is OK.

 

This leads me to suspect a capacitor is not working properly... as the only thing discharges in 1-2 minute are capacitors.

[Supersonicwolfe]

Also, the computer does wake up normally if I only put it to sleep instead of complete  shutdown.