Nvidia 790i Ultra Bad Caps Causing Problems?

Craterloads

Craterloads

Craterloads

Soldato
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Hi guys, whilst I'm confident that the caps are bad I just wanted to double check and would also like to know if it possible these caps are causing the issues with the motherboard.

It's a bit strange the behaviour but I have nailed it down to the motherboard after some experimenting.

For some reason the motherboard stock setting is only setting the CPU Voltage to 1.2v when the VID and stock Volts for the CPU should be 1.25V (QX9650). Also some of the other voltages set by the motherboard automatically seem a bit low when I compare to others online using the same CPU and board.

  • When using 1 Module of Ram and 1.2v CPU Core (auto set by motherboard) the system appears to run fine.
  • When using 4 Modules of RAM and 1.2v CPU Core (auto set by motherboard) the system will crash often and get stuck in the Windows load up.
  • When using 4 Modules of RAM and manually set the CPU Core 1.25v the system seems to be much more stable with only the odd crash.
Here are some pics of the of the caps I think are bad, are they?



Slight bulge


This one appears fine, nice and flat for comparison




Theres 4 caps in total that I think are bad, could these be having an affect on the DIMM slots and also making the boards stock auto volts low?

The caps read Sanyo 1500uF 6.3v (10mm x 20mm)

Ordered these - ** Do not link to competitors **
 
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I've read somewhere that capacitors @ motherboard should be replaced with pairs or chains, but I don't know why, and where I've found it.
Stability @ 790i Ultra depends on proper RAM sticks from QVL, at least it was @ my old Asus Striker II Extreme. I don't know why you raise CPU voltage having more workload @ northbridge (which has integrated memory controller); rather try to find some CPU-NB voltage option to raise.
 
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biuro74 said:
I've read somewhere that capacitors @ motherboard should be replaced with pairs or chains, but I don't know why, and where I've found it.
Stability @ 790i Ultra depends on proper RAM sticks from QVL, at least it was @ my old Asus Striker II Extreme. I don't know why you raise CPU voltage having more workload @ northbridge (which has integrated memory controller); rather try to find some CPU-NB voltage option to raise.
Click to expand...

Memory is fine and is the original shipped with the Dell XPS system, ran memtest on them and no errors.

1.2v is below spec for the QX9650 as everywhere I can see it should be 1.25v

Will have a look If there is a north bridge option.

System was fine hence why I was assuming the bulging caps had passed it and were causing the voltage issues now.
 
I would say

1. its fiddly as hell
2. its not always possible
3. you risk causing more damage
4. did I mention its really fiddly to do.
 
Make sure the caps you get are low esr or original caps if you can get some and replacement caps should be mounted and soldered as close as possible to the pcb.
 
Ploppy2k3 said:
I would say

1. its fiddly as hell
2. its not always possible
3. you risk causing more damage
4. did I mention its really fiddly to do.
Click to expand...

Just two solder points for each one and they are relatively spaced a good distance apart. Plus I bought a desoldering gun last month which will make removing them a breeze

AtaRo said:
Make sure the caps you get are low esr or original caps if you can get some and replacement caps should be mounted and soldered as close as possible to the pcb.
Click to expand...

I was going to get the original ones and had ordered them but now cancelled as someone suggested avoiding them and going for Rubycon MCZ caps instead which are low esr

Sanyo 1500uF 6.3v original

Rubycon MCZ 1500uF 10v

Apparently the 10v shouldn't be an issue and the UF is more important to match.
 
As long as the voltage rating is equal or higher than the original then it is good.

The more important is the capacitance, esr and the dimension as it could be a problem if the diameter is bigger especially in a tight space and Rubycon caps are good.
 
I would still be dubious about buying any capacitor from china particularly since rubycon MCZ and MBZ series were both discontinued in 2010. I'd have looked at the current rubycon ZL, Panasonic FM/FR or nichicon HZ/HN instead. You could use sanyo OS-CON SEPC instead which have almost unbelievable specs vs traditional aluminium electrolytics, but they cost a small fortune.
 
Kei said:
I would still be dubious about buying any capacitor from china particularly since rubycon MCZ and MBZ series were both discontinued in 2010. I'd have looked at the current rubycon ZL, Panasonic FM/FR or nichicon HZ/HN instead. You could use sanyo OS-CON SEPC instead which have almost unbelievable specs vs traditional aluminium electrolytics, but they cost a small fortune.
Click to expand...

I don't really know much about capacitors hence just going off advice.

Someone over at bad caps reccomended them and they also sell them but postage would have been too much.

This ebay seller is also trusted over at bad caps so thought it would be worth a shot for only £3. I'll post some pics of them when they arrive, guess it is easy enough to spot a fake?

The Sanyo ones you have linked are they low ESR?
 
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They'll probably be ok (just my own dubiousness), the folk over on badcaps seem to know most of the suppliers that are reputable. Those old rubycon MCZ & MBZ capacitors were very good when they were available. 4 years in storage isn't too bad, though caps do age faster when left unused.

The sanyo oscon's i linked to have extremely low ESR, and extremely high ripple. (Compared with the MCZ you've just bought, ripple is 5560mA vs 2350mA and ESR is 10mΩ vs 12mΩ)
 
Kei said:
They'll probably be ok (just my own dubiousness), the folk over on badcaps seem to know most of the suppliers that are reputable. Those old rubycon MCZ & MBZ capacitors were very good when they were available. 4 years in storage isn't too bad, though caps do age faster when left unused.

The sanyo oscon's i linked to have extremely low ESR, and extremely high ripple. (Compared with the MCZ you've just bought, ripple is 5560mA vs 2350mA and ESR is 10mΩ vs 12mΩ)
Click to expand...

Cheers will keep them in mind if these turn out to be duds. The MCZs are specifically mentioned over there and at seller pages for being ideal for motherboard replacements and given my knowledge level just went with what was advised as was in a bit of a rush.

Guess they will be still be an upgrade to whats installed now I guess!
 
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