Iwill MPX2 reboots under heavy load

[Slippery Jim]

Does this sound like a bad cap problem to anyone?

I have an Iwill MPX2 motherboard (rev. 1.3) that has been running fine with a single 512MB DIMM for about three years.

Recently, I decided to max out the RAM, so I went out and bought three 1GB DIMMS.

Now, whenever I have more than one DIMM plugged in, and I load the system, it reboots itself after between five and fifteen minutes.

With a single DIMM in, the system can handle anything I throw at it without blinking.

It doesn't matter what combination of DIMMs or DIMM slots I use; 1 DIMM is stable, more than one DIMM is not. The more DIMMs I install, the easier it is to get it to reboot itself.

I've done a lot of troubleshooting, and I know that the RAM, CPUs and add-in cards are good. I've tried three different PSUs (culminating in a PC&C TurboCool 850). I'm pretty sure there is something wrong with the motherboard. (Here's a link to my troubleshooting thread at 2cpu.com, in case you're interested).

The caps are Sanyo and Hermei. They look all right, and I don't notice any smell. The RAM and the heat sink on the voltage regulators do seem very hot to me.

[Tom41]

Re: Iwill MPX2 reboots under heavy load

It's always possible you've got RAM from a defective batch - have you tried another brand from a different shop?

The rebooting sounds to me like a cap problem. Some brands (e.g. Teapo) can fail without any physical signs, though Sanyo is usually a 'good' cap - not sure about Hermei though. Get a capacitance test meter and see if they all test OK for capacitance - if they don't, there's your trouble.

Even the best quality electrolytics will fail from time to time, and are more likely to fail if you put the circuit under a lot of stress. I've heard of Rubycon caps that have vented due to being put in the wrong way, and overdriving a board can cause good caps to go bad.

I'd usually ask to check the PSU, but you said you've tried 3 different PSUs all with the same problem. Unless all 3 of the PSUs have bad caps, that's probably not the problem. If the RAM is hot, it could be that the RAM is just drawing too much power from the PSU, not leaving enough to keep the system stable. Hot RAM and regulators do usually indicate a more severe problem though.

[Topcat]

Re: Iwill MPX2 reboots under heavy load

I had similar issues with Iwill boards before. I always found them to be BIOS issues. If I ran 4 DIMM's in my DVD266u-RN, it would do the same thing... Usually BIOS updates, or hacks would eliminate it. Iwill is known to be one of the most unstable boards in existance. I have seen Iwill's with bad caps, especially the Hermei's, but my gut tells me thats not the true source of your trouble.

[Slippery Jim]

Re: Iwill MPX2 reboots under heavy load

Get a capacitance test meter and see if they all test OK for capacitance - if they don't, there's your trouble.

Is it OK to use a meter on the cap while it is on the motherboard, or do I have to remove the cap first?

[gonzo0815]

Re: Iwill MPX2 reboots under heavy load

If you have an ESR meter, you probably can do it with the buggers soldered in. A normal Capacitance tester will probably fail, as ll caps are in parallel.
So i think get your hands on sucht an thing and test the caps on ESR.
But keep in mind, that those caps should be discharged and PSU has to be pluged off.

[kc8adu]

Re: Iwill MPX2 reboots under heavy load

If you have an ESR meter, you probably can do it with the buggers soldered in. A normal Capacitance tester will probably fail, as ll caps are in parallel.
So i think get your hands on sucht an thing and test the caps on ESR.
But keep in mind, that those caps should be discharged and PSU has to be pluged off.

many boards have mlcc at the sockets nowadays.the lytics can be open and you may get a low esr reading anyway.pull them to test.
if a known crap brand just replace them.
i would check vdimm with 1 module and again with all of them.check for proper voltage and also for noise/ripple.you will need a scope.

[Slippery Jim]

Re: Iwill MPX2 reboots under heavy load

many boards have mlcc at the sockets nowadays.the lytics can be open and you may get a low esr reading anyway.pull them to test.
if a known crap brand just replace them.
i would check vdimm with 1 module and again with all of them.check for proper voltage and also for noise/ripple.you will need a scope.

Er, i don't think I could pull them without wrecking the board. I tried to shorten the leads on one of my case fans yesterday. I just made a mess trying to solder the end connectors back on using a radio shack soldering iron. Melted the insulation and got blobs of solder everywhere.

Maybe I should just send the board to Topcat, and have him replace them all, as preventitive maintenance.

[Per Hansson]

Re: Iwill MPX2 reboots under heavy load

Well, what about the BIOS timings?

You will need to step down to 2T for example, and I doubt you will be able to run faster than 3-3-3-5 stable with that many DIMM's populated...

[Slippery Jim]

Re: Iwill MPX2 reboots under heavy load

Well, what about the BIOS timings?

You will need to step down to 2T for example, and I doubt you will be able to run faster than 3-3-3-5 stable with that many DIMM's populated...

I have tried using conservative timings, but they had no effect on the issue. I wouldn't think that two DIMMs would be too much for the board to handle, under normal operating conditions. This is a stock system; I'm not overclocking or volt modding.

[Per Hansson]

Re: Iwill MPX2 reboots under heavy load

Well, maybe your board has the same issue as mine then, which I have no solution at all too, but I do have a dang long thread describing it

https://www.badcaps.net/forum/showthread.php?t=1710

More likley though is that your mobo does not like that brand of RAM, try another brand from a friends computer or something and see how it goes...

[tazwegion]

Re: Iwill MPX2 reboots under heavy load

I think Per Hanson might be on the right track with his suggestion, I recently purchased some transcend DDR-2700 which ran superbly on their own... but would cause random errors and crashes when used in conjunction, the simple answer was to 'loosen' the timings at which the chips ran

Additionally, you could download Memtest86 and install it to a (OS independant) bootable floppy, this will allow a more specific means of troubleshooting RAM & timings etc. BTW it's free GPL software

[Topcat]

Re: Iwill MPX2 reboots under heavy load

Well, maybe your board has the same issue as mine then, which I have no solution at all too, but I do have a dang long thread describing it

https://www.badcaps.net/forum/showthread.php?t=1710

More likley though is that your mobo does not like that brand of RAM, try another brand from a friends computer or something and see how it goes...

Ahh, I did forget about that point.... My DVD266u-rn was also VERY finicky about what RAM I used in it. Good point!

[Slippery Jim]

Re: Iwill MPX2 reboots under heavy load

I have tried runnung it with the most relaxed timings I am able to set in the BIOS, so I don't think that's has any effect.

Also, it doesn't matter what FSB or CPU voltage I run at. I tried lowering both last night in small increments, just for the hell of it, to see if that would affect anything. No change in the reboot behaviour.

I put a temperature sensor on the heat sink over the voltage regulators, and they're running at 60+ degrees C. The 16V caps next to them are ~ 10C cooler that that. I put a fan over the heat sink to bring the temp down, but it didn't have any effect on the rebooting.

It seems to require some warm-up time before it starts rebooting. The first run is usually a bit longer than subsequent runs.

I'm using crucial registered ECC 2700 DIMMs in it currently. Thing is, it's a real pain in the ass to get 1GB sticks for this board, because it won't take RAM built with 512Mbit chips. I had to RMA twice to get DIMMs that would even POST in this board.

Also, If I put a voltmeter between the vent on a cap and ground, I get a voltage reading. Which lead is the vent attached to?

[gonzo0815]

Re: Iwill MPX2 reboots under heavy load

Theoreticall is should be ground IMHO, but i mesured on may boards some voltage against ground.

[Slippery Jim]

Re: Iwill MPX2 reboots under heavy load

Theoreticall is should be ground IMHO, but i mesured on may boards some voltage against ground.

Yeah, I get get different readings from each cap, typically in the range of 40mV to 350mV. The voltage slowly drops if I keep the probe on the vent. I guess this is due to the multimeter drawing a small current when it makes the measurement.

I wonder if it's the ripple I'm reading. My understanding is that these lytics' negative leads are connected to ground, to draw off any ripple from the DC signal on the positive lead (is my polarity correct in this statement?). If the frequency is high enough, then I bet my meter would read constant DC current equal to p-p of the ripple (or RMS of ripple?).