5820k missing resistor

[ProfessorShroom]

A customer brought his PC in not posting, the CPU is missing a resistor on the bottom. Does anyone know if this resistor is actually needed and what resistor is it so I can solder on a replacement?

 

[SpiralTTGL]

why not look up the cpu and see if it has it or not?

 

also being as non descriptive as possible is bonus points for this post

[ProfessorShroom]

How is that undescriptive? I've told you the model and shown you a photo. You know as much as I do.

 

Can't find much info online about the resistors

[CodeNova]

4 minutes ago, ProfessorShroom said:

A customer brought his PC in not posting, the CPU is missing a resistor on the bottom. Does anyone know if this resistor is actually needed and what resistor is it so I can solder on a replacement?

 

<snip>

It looks like a filter cap, based on the package size. It also looks like the pad was lifted, fixing it might not be an option.

[ProfessorShroom]

Thanks! One pad is okay, one looks slightly lifted but now all of it so might be repairable. Any ideas on what filter cap?

[SpiralTTGL]

2 minutes ago, CodeNova said:

It looks like a filter cap, based on the package size. It also looks like the pad was lifted, fixing it might not be an option.

kinda looks like bare copper on the top side and bottom pad looks intact it might just workout

[CodeNova]

6 minutes ago, ProfessorShroom said:

Thanks! One pad is okay, one looks slightly lifted but now all of it so might be repairable. Any ideas on what filter cap?

if it is a filter cap (I have no real way of knowing), ya don't need it, its just there to reduce ripple. You could always 'carefully' remove the one next to it, then measure its capacitance. Us folks tend to use the same parts to reduce manufacturing costs. Ex. buy one really big cap at 0.50, or two small caps at 0.10.

[mariushm]

It's a capacitor. There's so many different ceramic capacitors with so many different parameters (and in this case those parameters actually MATTER) that you can't just use any capacitor and be confident there won't be any problems.

Best best would be to find a dead cpu from the same family/series (same socket) and about the same TDP and desolder the capacitor from that faulty cpu and solder it to your cpu.

 

As for actual value, it's high probability it's same value as the one on the left... I'd guess something like 1uF - 10uF 6.3v..10v ... but again,the other technical parameters for that capacitor matter.

I'm not sure, but I'd say they're used for additional filtering of the input power... so if that's the case and if you're unlucky, then the lack of this capacitor could cause the cpu to not boost as often to the highest frequencies or in rare cases you may experience crashes in programs (think of it like when a core tries to switch from a low frequency to a higher frequency, the sudden extra power consumption can cause the input voltage to fluctuate a bit and the capacitor is not there to help the voltage stabilize fast enough)

 

[CodeNova]

1 minute ago, mariushm said:

Best best would be to find a dead cpu from the same family/series (same socket) and about the same TDP and desolder the capacitor from that faulty cpu and solder it to your cpu.

 

I never thought of a donor, that is the best solution.

[CodeNova]

@ProfessorShroom, Just to rule it out, or confirm, see if it posts with another CPU. It could be a different problem completely.

 

Edit: To a hammer, everything looks like a nail.

[ProfessorShroom]

Thanks everyone for the suggestions. The only processor with a similar capacitor we had lying around worth destroying was a poor Core 2 Duo, soldered the capacitor onto the 5820k and it posts!

[mariushm]

Well, like I said... it probably would have posted with any capacitor soldered there, but the actual capacitance value and the specs will matter. Your cpu may crash randomly or not reach the turbo frequencies until you install a more suitable capacitor.

Anyway, at least you know it's not a dead cpu.