Doesn't quite work that way, and good job on capacitor replacement
What bites is sometimes the Electrolytic Paste dries up, and there is no visual signs of failure.
1) Think I better tell you about the motherboard voltage regulator circuit;
One of the things the motherboard voltage regulator circuit does, is to regulate voltage for the Processor. (CPU)
The Processor MUST have a steady, 'clean', supply of voltage; and it MUST be kept within the tight voltage tolerance range, specified for the Processor.
Cannot be too much, or too little; or BIOS turns it off.http://www.hardwaresecrets.com/article/616
General thinking would be that the Capacitors that surround the Processor, are the only ones for it.
This is a fallacy.
There could a capacitor, or capacitors; that are in the motherboard voltage regulator circuit, and for the Processor; and are NO where near the Processor.
You actually have to follow the circuit traces, and see.
Example; Is there a capacitor over by the Ram Memory, or another outlying area, that a circuit trace from it leads to the processor socket?
Read the Hardwaresecrets article, and I believe it will help with understanding.
2) Don't know your soldering prowess, not knocking it.
You don't have any cold solder joints, do you?
That will make you pull your hair out, until you find it.
3) The Power Supply thing; the statement that it doesn't work that way;
You could have a Power Supply with a weak voltage power rail.
LED's would light up, and fans may spin; but there isn't enough power to turn the Processor on.
1) If ALL of the LED's were lit up at once, they would use less than 1 Watt of power.
2) EACH fan uses 2 to 3 Watts of power.
3) A typical Processor (CPU) can use 51 to 125 Watts of power.
Just depends on what Processor it is.
When testing; the Processor, processor fan and heatsink, plus ram memory is installed.
You are trying to get the BIOS Setup screen to come up.
Make SURE there is a stick of ram memory in Slot 1. (DIMM 1)
This is the ram memory slot that is closest to the Processor.
The Processor reads Slot 1 first.
Yes. If you have more than 1 ram memory module ('Stick'), trade them around/out, and see if you have a bad ram memory module.
Also suggest clean the gold plated contact pins, on the Ram Memory module; with a pencil eraser.
Use air to remove the eraser dust.
When diagnosing a desktop computer problem, POWER is ALWAYS checked first.
Then see if computer is dirty inside, and then clean ram memory module's, gold plated contact pins with pencil eraser.
If you are not following, or if the person before you was not following; Anti-Static Procedures, use the motherboards for a Frisbee, or expensive paperweight.
There are 3 main voltage power rails;
A) 3.3 Volts
B) 5 Volts
C) 12 Volts
ALL are DC Voltage
In comparison two D cell flashlight batteries produce 3 Volts DC.
A) ALL Orange wires are 3.3 Volts
B) ALL Red wires are 5 Volts
C) ALL Yellow wires are 12 Volts.
ALL Black wires are Ground wires.
Voltage power rail.
ALL Orange wires are 3.3 Volts, and they all end in one central point; inside the power supply; the 3.3 Volt power rail.
Same thing for Red 5 Volt wires, and Yellow 12 Volt wires.
Multimeter red probe lead (Positive) plugged into Red hole on multimeter, that has DCV next to it. DC Voltage.
Function knob set to DC Voltage (DCV)
If just a symbol, the symbol is a dotted line over a solid line.
(Curved line over solid line is ACV. AC Voltage)
If more than one scale, set to 0-50 volt scale, DCV.
0 to 50 volts Direct Current Voltage. (DC Voltage)
Positive (Red) probe lead of multimeter TO power wires.
3.3 Volt (Orange), 5 Volt (Red), 12 Volt (Yellow)
Negative (Black) probe lead of multimeter TO Ground wire.
ALL Black wires are Ground wires.
(Power supply on)
You can purchase an economical multimeter, for as little as $5 to $12.
Auto parts stores have them. (A little more pricey usually)
I have seen them on checkout aisle racks, at major discount stores.
Is there a working computer you can TEMPORARILY, borrow it's Power Supply?
KNOWN to be working, and Compatible Power Supply?
Use for a test unit. See if the Power Supply is the problem.
Not to be a hater, but I would use SuperMicro motherboards; to skip across the lake with.
"Wow! Look at that baby go!"
But DON'T! It's bad on the environment.
(Fish get two heads, and stuff.
NO! Not really. You gonna' believe that? lol!
It IS bad for the environment, however)http://en.wikipedia.org/wiki/Computer_power_supply#Wiring_diagramshttp://en.wikipedia.org/wiki/Computer_power_supply
For additional questions please post in a Comment.