There are 2 Kinds of Light patterns.

http://www.dell.com/support/Article/cn/en/cndhs1/636727/EN

 

SOLID is not the same as flashing.

The Precision T3500/T5500/T7500 Workstations are equipped with diagnostic and status lights. There are numbered lights, 1-4, and the power button also serves as a status indicator.

Depending on the status of the system, the power button light may be green or amber and may be off, solid, or blinking. There are five total power button light states:

• No light — System is in the off state (S5, or mechanical (AC power not applied) OFF).
• Solid Amber — System fault, but Power Supply is good—normal operating state (S0).
• Blinking Amber — System fault error condition including Power Supply (only +5VSB working), Vreg failure, missing or bad CPU.
• Blinking Green — System is in power saving states S1, S3 or S4. (Blink rate is 1Hz). No fault/error condition.
• Solid Green — System is fully functional and is in S0 (ON) state.

Four (4) single color LEDs are incorporated on the front control panel to serve as a diagnostic aid for troubleshooting systems exhibiting No Post/ No Video symptoms. The LEDs do NOT report runtime errors. The LEDs are numbered 1-4 and are located on the front panel, between the audio jacks and the front USB ports. Additionally, there are LEDs to indicate network and hard drive activity. You can see these LEDs in the image below.

Pb12

1-Blink 2-Blink 3- Off 4- Off

System board Regulator Failure

A power failure has been detected in one of the onboard system board regulators. This could be caused by a failed system board component or by a plug-in device creating a short on a regulated power rail. (PS_ON asserted, PS_PWRGOOD asserted, SYS_PWRGOOD de-asserted)

 

What color is the power button, and is it steady or blinking?

Any beeps?

Try clearing BIOS:

1. Power off, unplug
2. Press/hold power button for ~15 sec
3. Open case and remove motherboard battery
4. Press/hold power button for ~30 sec
5. Carefully reseat RAM modules and PCI cards in their slots
6. Reinstall battery (right-side-up!)
7. Close case and see if it boots with only mouse, monitor, and keyboard connected

If that doesn't help, you may need to remove RAM modules according to the table of supported configurations in the manual (p41) to see if you have a bad RAM module or maybe a slot problem.

 

 

Hello Well I have unplugged everything that I can think of to unplug remove and or un-power and I still get the same Pb12 1- Blink 2- Blink 3- Off 4- Off System board Regulator Failure A power failure has been detected in one of the onboard system board regulators. This could be caused by a failed system board component or by a plug-in device creating a short on a regulated power rail. (PS_ON asserted, PS_PWRGOOD asserted, SYS_PWRGOOD de-asserted) error message , which suggests to me there is a problem on the mother board, Having already replaced the PSU I suspect it time to use what I have for spares and use what I have to build a newer system. Of course if you know something else I can try I am all ears. Thanks for all your assistance

hello, I have tried all of these suggestions above, but so far there has been no change. I still get the same response , no 1 and 2 flashing green then nothing. I beginning to suspect its a system board issue.