Biostar G41-M7 strange behavior

[alindumitru46]

This is a part of a old computer with E7400, 2x2GB DDR2 RAM and GT430 videocard, used by a person immobilized in a trolley.
I thought it deserved an attempt to fix it, as investment in a new computer is quite large, considering it is used only for online browsing and watching movies.
I've made a "discharging" of compressed air and isopropyl alcohol.
I checked the video card and memory and they started from the first. I tested the motherboard with 1 memory stick. After attaching a hdd, I noticed that in configuration with 2x 2GB does not boot.
RAM sticks works separately, slots works separately, but not together.
The solid capacitor(270uF/16V) by the side of IDE slot is warming up abnormally, by touch.
I suspect a voltage problem that does not provide voltage for the RAM, but I am not convinced if it is due to capacitor issue or FET(NIKOS P09003bdg and FP6321 Synchronous Buck PWM DC-DC Controller) issue (low voltage or rather it is not properly rectified?!)

[momaka]

I have the G31-M7 motherboard, which appears nearly identical to what you have. Mine came with many bulging/failed OST capacitors.
So if there is anything to suspect, it would be those OST capacitors. I suggest changing them first (or pulling them and testing them with an ESR/capacitance meter) before anything else - at least the ones around the RAM.

Also, do you have any 512 MB single-sided memory modules? (i.e. RAM with chips only on one side?) Sometimes, those use a bit less power than their 2-sided friends. It might be low enough that the board posts with both modules in both slots. If that's the case, I would bet even more money it's the OST caps.

*EDIT*
Looking closer at my motherboard, I think that 16V/270 uF poly is for the high-side of the Northbridge buck regulator. Actually, my board originally had an OST RLX 6.3V, 1000 uF cap in there... and bulged. So that RAM "trick" might not work. But try it anyways.

[alindumitru46]

Thanks to your previous advices, changing capacitors is no longer a problem for now.
I'll try with single sided memories, but a 2x2GB single sided memory kit is more complicated to look for when it already has one.
The version of mobo is 6.4

[Drack]

What's the voltage on that capacitor? If it's between 1.1(most likely) and 1.2(highest supported by most mobos with g41 chipset) is for the Northridge, and if it's close to 1.8 should be for the ram, I know that this will not solve your problem but it would be nice to know if that capacitor is part of the issue.
What brand are the other caps on the motherboard?

[alindumitru46]

Cpu: 1500uF, 16V KZG NCKN,
Ram: 1000uF, 10V RLG OST, 1000uF, 6.3V RLX OST
The poly is 270uF, 16V RP by "?!?"

[Drack]

You should take that poly that's heating up out of the board and replace it temporarily for a low esr (a 820uf or 1000) or another polymer cap and check if it works. Some caps can fail in a manner that they create a partial short and heat up quite a bit.

Drack.