I need a replacement PSU for DELL Precision WorkStation 670. Where can I buy one?

You will need audio driver, possibly Network adapter driver and in some cases you may need to find the manufacturer of your optical drive by pulling out of the case to get model type and then the the driver from the manufacturer's site. Finally a chipset driver. check this site for most of the drivers.

http://www.dell.com/support/drivers/us/en/19/product/precision-670

http://www.dell.com/support/Manuals/us/en/19/Product/precision-470

Click on -
Dell Precision Workstation 470 and 670 Computer User's Guide

In the list on the right side, click on - Tools to Help Solve Problems

In the list on the left side, click on - Diagnostic Lights

Yellow (A) Green (B) Yellow (C)

"A possible VRM 1 failure has occurred"

VRM stands for Voltage Regulator Module.

It regulates Voltage for the Processor.

The Processor MUST have a steady, 'clean', supply of Voltage; and it MUST be kept within the tight voltage range, for the Processor.

Too little, or too much; and the Processor turns off. (BIOS turns it off)

Your motherboard supports two Processors.

1) Processor (CPU_0) Zero which is in the middle of the motherboard, next to the PCI Express x16 slot;

2) and Processor (CPU_1) One, which is next to it.

The VRM 1 has failed. Needs to be replaced.

http://www.ebay.com/itm/DELL-H2703-PRECISION-470-670-VRM-VOLTAGE-REGULATOR-MODULE-TH-0H2703-WS470-WS670-/380369885440

VRM's used are interchangeable.

IMHO you can remove Processor 1 (CPU_1), and it's VRM, and still use the computer; albiet slower though.

For additional questions please post in a Comment.
Regards,
joecoolvette

Try looking here:
http://www.dell.com/support/article/us/en/19/sln115082/resolve-usb-port-not-working-issues?lang=en

Do the sys support all those RAMS? Do a test take the new RAM out !

It is CMOS battery cell.You can buy it from nearest computer shop. It looks like below image. Click here It is CMOS cell which give voltage to bios to save data. Let me know if you need further assistance. Thanks for using FixYa.

DONT EVER UPDATE BIOS....99.99% IT WILL MAKE UR PC A DUD....MFGS DONT MAKE NEW UPDATES FOR OLD BIOS...AS BIOS CHIPS ARE HARDWARE MFG SPECIFIC...IF U STILL WANT TO DO...U NEED TO BE 1000000% SURE OF WHAT BIOS IS IN UR MACHINE AND WHAT BIOS SOFTWARE IS INSIDE THAT.....EVEN I AS AN EXPERT DONT ATEMPT IT....AS ANY CHANGE TO BIOS IS DIFFICULT TO REVERSE....
writing in all caps amounts to shouting....
sorry i wrote it in capital....not ment to shout at u...
just warning u

How many beeps? Any pattern? (e.g., short, short, long, long, low, high) ?

Contact Dell, and purchase a replacement motherboard.

You need the EXACT speed rated RAM.
Your support page states it needs.....
400-MHz DDR2 SDRAM
NOTE: Your computer supports only registered memory

Memory capacities
256-MB, 512-MB, 1-GB, 2-GB, and 4-GB ECC

256-MB, 512-MB, 1-GB, 2-GB, and 4-GB ECC modules to a max of 16GB
more info here
http://support.dell.com/support/edocs/systems/ws470/en/ug_en/about.htm

Did you change BIOS settings or does your BIOS supports dual processors?

Ok go to bios setup and then "load bios default" and press "F10" to save and exit. i will tell you in case this not work just tell me.