Installing missing caps on motherboards

[Pentium4]

I've never really thought much about adding missing caps, but on this Asus motherboard it looks like there is only one cap for RAM filtering. Would this benefit much from adding 820uF 6.3V nichicon HN caps? I was planning on leaving that Apaq if the added caps would help it. I think this motherboard has around 10K hours on it (Had lots of failed TK caps)

Since this is an Asus board, there are quite a bit of caps that weren't installed throughout the board.

*OT* I hate how Asus installs their caps to make it look like they're in backwards

[momaka]

Re: Installing missing caps on motherboards

Looks like a synchronous buck type of regulator circuit is used for the RAM, so adding caps probably wouldn't be a bad idea at all.

Also, since this is a P5 motherboard, have a look at this thread:
https://www.badcaps.net/forum/showthread.php?t=32502

And yeah, if you're not careful, it is easy to put caps in backwards on those ASUS motherboards. For me, I've done more ASUS recaps than other motherboard brand, so I have to be careful not to put caps in backwards on "normal" motherboards .

[Pentium4]

Re: Installing missing caps on motherboards

Thanks for the reply. This thing has been in one of my daily rigs since the 29th so I guess I'll just solder on those HN's when I've got some down time on it. i was looking at pictures of other P5KPL-CM's and some use 2 or 3 KZG's, I guess one polymer was enough to get the job done for filtering. Although I don't 100% trust Apaq polymers, the board is getting low ripple from a good recapped PSU.

I saw that thread, and I will keep it in mind yeah, I had to catch myself a few times!!

[brethin]

Re: Installing missing caps on motherboards

Thanks for the reply. This thing has been in one of my daily rigs since the 29th so I guess I'll just solder on those HN's when I've got some down time on it. i was looking at pictures of other P5KPL-CM's and some use 2 or 3 KZG's, I guess one polymer was enough to get the job done for filtering. Although I don't 100% trust Apaq polymers, the board is getting low ripple from a good recapped PSU.

I saw that thread, and I will keep it in mind yeah, I had to catch myself a few times!!

This is one reason I like ASUS. They use a good cap instead of filling it full of shit caps (for the most part). I normally fill in all the empty cap slots on the ASUS boards to help with ripple but just make sure you know if they are in series or parallel so as not to change the circuit capacitance too much (some is fine in most cases).

[momaka]

Re: Installing missing caps on motherboards

I guess one polymer was enough to get the job done for filtering. Although I don't 100% trust Apaq polymers, the board is getting low ripple from a good recapped PSU.

In synchronous buck regulators (like that one), I always like to see at least 2 caps or more doing the filtering. Relying on only one capacitor is just asking for trouble if something was to happen with that cap.

Lately, I got another E-VGA 7600 GT with cooked RAM chips due to failed Sacon FZ. The problem with that video card (besides the caps) is the buck regulator for the RAM has only one cap for the output, and when that cap goes bad, the inductor overheats and cooks itself. When that happens, you just have the MOSFETs sending pulsed 12V to the RAM chips, which are rated for.... 2.5V absolute max. And that's it for them.

[theOracle]

Re: Installing missing caps on motherboards

what makes you guys think that if the capacitors were deleted from the final design, that the circuit traces are still live to them?

[c_hegge]

Re: Installing missing caps on motherboards

^
In all likelihood, they weren't completely removed from the design. They were just not installed in order to cut costs. Usually, If I'm considering installing additional caps, I just check with a DMM that the empty slots are actually connected in parallel with the caps next to them.

[Kiriakos GR]

Re: Installing missing caps on motherboards

This motherboard looks to not have been planed to be a monster high-performance board for overclocking, therefore all the set of capacitors are calculated according to it capabilities.
Capacitors are cheep for such industries, they did not use additional because this specific motherboard does not need them.

[Pentium4]

Re: Installing missing caps on motherboards

I'd like to see at least another cap there too but that poly does has a ripple rating of 6100mA which seems like plenty for two RAM sticks that won't be getting overclocked. Still might add some caps when it's down, like when I upgrade the Core 2 Duo to a Core 2 Quad Would it be worth the effort to replace the Apaq's with some higher quality polymers?

[Pentium4]

Re: Installing missing caps on motherboards

Sweet! I found a couple hiding at work. A Q6600 (2.4GHz/8M/1066) and a Q8200 (2.33GHz/4M/1333). Stock, which one would be better? I'm thinking the faster FSB would be better than more cache, but the Q8200 also has 10TDP less.

[c_hegge]

Re: Installing missing caps on motherboards

Would it be worth the effort to replace the Apaq's with some higher quality polymers?

You think it actually take effort to replace a cap?!

Yeah, I would say go for it.

As for the CPUs, I'd say both would be similar in terms of performance.

[Pentium4]

Re: Installing missing caps on motherboards

You think it actually take effort to replace a cap?!

Yeah, I would say go for it.

As for the CPUs, I'd say both would be similar in terms of performance.

On an Asus board, yeah I'm slow at soldering on motherboards cause I'm used to the bigger joints on PSU's

As for the CPUs, I'd say both would be similar in terms of performance.

Yeah, I figured. I think I will go with the Q8200 because it's 45nm

[brethin]

Re: Installing missing caps on motherboards

what makes you guys think that if the capacitors were deleted from the final design, that the circuit traces are still live to them?

My eyes and a meter for starters. It would cost them more to retool the line to not include the circuit traces in most cases when producing the boards.

[brethin]

Re: Installing missing caps on motherboards

This motherboard looks to not have been planed to be a monster high-performance board for overclocking, therefore all the set of capacitors are calculated according to it capabilities.
Capacitors are cheep for such industries, they did not use additional because this specific motherboard does not need them.

Unless you want to add ripple protection above what they think it needs. And in most cases it helps.

[brethin]

Re: Installing missing caps on motherboards

Sweet! I found a couple hiding at work. A Q6600 (2.4GHz/8M/1066) and a Q8200 (2.33GHz/4M/1333). Stock, which one would be better? I'm thinking the faster FSB would be better than more cache, but the Q8200 also has 10TDP less.

If you are overclocking and your motherboard supports 1600FSB try the Q6600 first it may run at 1600 if not the Q8200 will unless its a really bad chip.

If you are not overclocking then go with the Q8200 for the lower TDP.

[Pentium4]

Re: Installing missing caps on motherboards

I'm running stock so I decided to go with the Q8200. brethin, what values do you normally add when you are installed the missing capacitors, just the same values that are in the vicinity or do you measure voltage and just add something like 1000uF caps?

[c_hegge]

Re: Installing missing caps on motherboards

Assuming they are in parallel, then I'd just use the same as the other nearby caps (in your case, I'd go with 560uF polies)

[lti]

Re: Installing missing caps on motherboards

what makes you guys think that if the capacitors were deleted from the final design, that the circuit traces are still live to them?

Why would they remove the traces and leave the holes and silkscreen markings?

[mariushm]

Re: Installing missing caps on motherboards

There can be other explanations for this.

They could have designed the board that way to give them option to use cheaper electrolytics and parallel them for lower esr. The esr was probably low enough with a single polymer capacitor so they had no need to fill the other locations.

Other explanations... could be that the designer just copy pasted the whole circuit for the memory from a similar model with 4 memory slots. Or maybe the design changed at the last moment.

Anyway, this particular board.. they cheaped out quite a bit on everything. They dropped the capacitors by the pci slots, the ones for the pci express... some pci cards could be unstable but I guess they just figured nobody uses quality pci cards anymore.

[c_hegge]

Re: Installing missing caps on motherboards

Anyway, this particular board.. they cheaped out quite a bit on everything...

Of course they did. It's ASUS after all.