thermal shutdown?

[jcrepes]

Hi all,

Yesterday, PC abruptly shutdown twice. No warning at all, similar to a power cut. Check the PC and the Power LED was on. Had to turn off the switch on the PSU and turn it back on to restart the PC. I suspect it could be a thermal problem becos the weather was very hot.

My mobo is a Gigabyte GA-7N400 Pro (brand new!), XP1700+, Globalwin CAK4-88T heatsink+fan, 80mm case fan, vga cooler, 512mb PC3200, 500watt PSU.

When I checked the temperature using MBM5.3.3, system temperature 38C, CPU 30C (?!). I don't think it is possible for the CPU temp to be lower than system temp.

Can anyone please help? Thanks

 

[svol]

It is probably 38 C CPU and 30 C system, the hardware monitor chip is probablty set wrong in MBM 5, just change them to get them right.

With those temps I would be looking towards a voltage issue. But try running Toast for a couple of hours on your PC and see if the CPU gets very high.

I love my Delta 60HP 7000 RPM fan that puts out more dB then CFM

 

[jcrepes]

Thanks svol. You are probably right about MBM5. The BIOS reading is worst, SYSTEM 33C, CPU 14C (?). Yesterday I ran seti@home to test the stability. CPU temp rose to 41C in MBM, case temp 29C. I think +5V is about 4.08V, a bit low I think. Most readings were constant except for -12V, huge fluctuations between -11V to 0.3V. And it did shutdown once after about 2 hours. Any ideas?
Thanks

 

[Maverick494]

Your -12V rail got all the way down to -0.3V!? I think you may need to start investigating a new power supply. That is very odd and not a good sign. Your 12V rails should really never get below about 11.8V to be really stable. As your load (current draw) increases voltage will drop a little because it isn't a perfect circuit. However if you do the math then you will see that there is no way you should get down to less than 1V.

Power(P) = Current(I) x Voltage (V)

Current(I) = Voltage(V) / Resistance(R)

now I don't know about your PSU, but usually the 12V rails are rated to provide 15A (I).

P = 15 x 12

180Watts of power avail for the 12V rail at full capacity (theoretically)

in your case though you have this:

P = 15 x .3

4.5Watts available.

Big difference there and a medium sized fan can draw that much power by itself. So the instability is due to that 12V rail not being able to sustain the load you are demanding of it. PSU replacement is reccomended. It could've died because it got hot or it could just have worn out. Bottom line is that something isn't working right.





Just a computer junky

 

[svol]

Ignore the -12V readings, they're fake and unimportant. I would worry more about the 5V rail.

What kind of brand is your PSU?

I love my Delta 60HP 7000 RPM fan that puts out more dB then CFM

 

[TheMASK]

Heya svol,
MBM 5 shows the following readings in my comp:
+5V - 4.95; +12V - 13.31; +3.3V - 3.31V.
I am kinda anxious about the +12V. is it a little high? I am using a generic PSU.

<b>thinking of a good sig. till then...</b>

 

[pIII_Man]

It is exxtremely high...if you have a volt meter i would recomend taking some readings with that as opposed to a program...i find that they are sometimes a bit off...but that is 1v above what it should be! Still check the yellow wire of a molex connector to be sure.

There is no smell better than fried silicon

 

[TheMASK]

The molex connector is the one u connect to the HDD, Optical Drives right? I just checked the Yellow Line on this HDD connector and i got a reading of 11.19V. so thats pretty OK i guess. or do i need to worry?

<b>i wish i had a <font color=red>million</font color=red> <font color=green>$$$</font color=green>...</b>

 

[pIII_Man]

that is very low...i sudgest you change that power supply...yes you did measure right...

There is no smell better than fried silicon

 

[TheMASK]

Well, the PSU i hae right now is the "BEST" i cud get around here. It cost me thrice as much as the normal PSUs u get here. The computer shop that got me this PSU, which is a Generic 500W (Brand name - Zebronics, 420W True Power), actually thot I was crazy to be spending so much on just a PSU. I am still looking for Enermax and Antec brands here.

<b>One mood, all the time.</b>

 

[jcrepes]

Svol,

So it's safe to ignore the -ve 12V reading? MY PSU is abt 1yr old, can't remember the brand. I think its generic but with 2 fans and aluminium case. It's seems to be working fine before I swapped my Abit KD7-Raid for the Gigabyte GA-7N400Pro.

I think my Abit mobo is dead. Had a couple of corrupted CMOS errors.

 

[svol]

Well you might want to do a manual reading with a multi-meter. Just read the voltage between the blue and black wire. But I've seen very much mobo's giving false -12V readings. But if the reading is also there inside the BIOS and with the default reading rpogram I would do a manual reading for sure.

I love my Delta 60HP 7000 RPM fan that puts out more dB then CFM

 

[pIII_Man]

indeed onboard voltage readings of any kind are normally wrong...the only ones that i have found to be consistantly right with the multimeter is the Vcore...

There is no smell better than fried silicon

 

[svol]

That is because the mobo places some filters at every rail that comes in through the connector and also brings the rails down to the Vdimm, VI/O, Vcore and Vagp voltages.

I love my Delta 60HP 7000 RPM fan that puts out more dB then CFM

 

[pIII_Man]

correct...even a great power supply needs to be futher filtered...

There is no smell better than fried silicon

 

[svol]

Yeah, that is because all 5V and 12V wires in a PSU are feed from the same rail... so if you suddenlty turn on a hihg power device the fluctuation can do damge to your mobo if it wasn't filtered.

I love my Delta 60HP 7000 RPM fan that puts out more dB then CFM