Minus temps causing machine lockup?

[mjh74]

Hi all,

I started to have problems with my PC after about 3 months of using this Mach II GT. It's an Asus P4C800E-Dlx mobo with a precott 3.2 running at 4.2. For no reason the machine started to freeze and the only way of getting it back on was to power off and on. I lowered everything back to stock settings and the lockups still occured after a minute/hour/3 hours. I removed everthing to check the board for condensation damage and all seemed ok. I ran the machine with a thermalright SLU900 heatsink and fan at stock speeds for about 4 days under hard load (2 session of prime95), chip running at 68c (eek), not a single crash. Just incase, I thought I'd "condensation proof" the back of the motherboard and around the CPU socket with silicone sealant and fill the CPU pin holes with some dow corning DC4 before trying again. I finally degreased where the seal string would go with switch cleaner and put it all back together. Used a double layer of seal string as I did initially and set it running at stock speeds. With 2 sessions of prime95 running and the CPU sitting at -16c, all seemed well until this morning. 13 hours later and the machine started to lockup again . I have no idea what could be causing the problem that I never had with a heatsink and fan.

Any ideas would be greatly appreciated,

Mark

 

[Phil Stanbridge]

hmm this is a weird one mate, honestly it sounds like it was condensation related - what else can it possibly be, especially as you mention it happens after several hours which is typical. Dont forget only a small amount is enough to cause freezes/crashes and it could be that it dried up before you got to take it apart. I am certain this is the case.

Things to check : only use the minimum amount of string on the cpukit, and check for air gaps prior to installation. Make sure you get good contact.

Cover the screw heads on the back and front with string and make sure its completely sealed! This is important as you'd be amazed how the condensation forms in the screw holes. I once left off the string purposely as an experiment, and upon removal the screws had rusted.

 

[mjh74]

Hi Phil,

Thanks for the reply. I'm*almost* certain, or should I at least say it's looking like it could be a break in one of the tracks on the motherboard. I'm going to go around it with an eye glass tomorrow and see what I can find. Slight pressure on the board can make the difference between it powering on or not, it can then be fine for hours . I'm 95% confident that the seal is good. I even degreased my damn fingers as well as around the CPU socket before I put on the string! .

Another concern is a dry joint with one of the small surface mount resistors or caps or even a mosfet. I'm getting an amazing amount of heat from 8 of the mosfets around the board and even with large copper ramsinks silver epoxied to them, the sinks themselves are absolutely untouchable. There are 2 that fall under the seal string so theres no way to remove heat from them . I'm very much regretting getting this prescott chip....

 

[aXeR]

that is indeed weird, if your sure it isnt condensation then my next guess would be due to power, leabe something like asus prober running on your PC, set it to 'record' it will monitor voltage across all the rails, any spikes *should* show!

What gfx card are you using? the X800 series can cuase system hangs if overclocked and no extra voltage is given to them, i noticed this first hand hense i did the pencil mod, since doing this I havent been getting any lock ups

 

[mjh74]

Well I haven't touched anything yet but just powered on the machine and the evap head is constantly whistling and the temp is showing -30 on the display, cpu is now +3 when it was -18 under full load the other day. <sigh>

I guess my new prommie is bugg3r3d

 

[Wingz]

sounds like theres a leak somewhere :/

Well I haven't touched anything yet but just powered on the machine and the evap head is constantly whistling and the temp is showing -30 on the display, cpu is now +3 when it was -18 under full load the other day. <sigh>

I guess my new prommie is bugg3r3d

 

[mjh74]

I have only had the head off once and been very careful about it too. Any suggestions as what to do now anyone?

 

[mjh74]

Hmmm It used to whistle like this when powering on since I had it whilst it was cooling down to temp, it would pretty much carry on down to -63 and the sound would fade out. It's almost died down again now but the temp shows -33 and cpu -2 loaded, something isn't right. Maybe I don't have a motherboard problem after all and it's a prommie issue. Guru's, I need help please when about.

TIA!

 

[aXeR]

the whistling sounds a bit worrying, its a while since i had my prommie now so i cant swear to it, but i cant remember mine ever whistling :S

Phil is the man you want to talk too

 

[mjh74]

Philllllllllllllllllllllllllllllllllllllllllll *calls loudly*

 

[Phil Stanbridge]

Can you hear gas escaping at all? My GT had a small hole in the tube - it got to the point where it wouldnt reach boot temp as it couldnt get cold enough, sounds like what you're experiencing.

 

[mjh74]

Hmmm is that what the change pitch whistling sound could be? Though it has done it since the day I first powered it on but it would die down when reaching it's coolest temp. Without sounding totally "derrr", would the sound of the gas escaping be a hiss?

 

[Phil Stanbridge]

Hmmm is that what the change pitch whistling sound could be? Though it has done it since the day I first powered it on but it would die down when reaching it's coolest temp. Without sounding totally "derrr", would the sound of the gas escaping be a hiss?

I think that whine you hear is perfectly normal - I get that with this regassed Mach II here. What I mean is literally escaping gas, sounding like a hiss.

 

[mjh74]

Ahhh, well definitely no hiss and last night after a few hours it got the CPU whilst under 50% load down to -7c and the display was reading -47c. The strange thing is, since this weird behaviour the PC hasn't crashed once, I'm totally confused. :/

 

[mjh74]

And tonight it's all over the shop. First powered on at it got down to -53c, CPU at -11c half load. Then the LCD display showed -22c and CPU temps of +4, now I am watching the LCD display creep back down to -37c at the minute and nothing has changed, CPU at -7c again. What on earth is it doing??

 

[ZaX]

Why don't you get a qualified AC engineer to look at it.

 

[Phil Stanbridge]

I'll take a look at it if you can send it to me and have it collected. I wont charge you anything.

 

[dillingerdan]

I actually have a high pitched whine that comes from my machine! I think it is the fans when they run in high speed mode to get the temperature down! Also I have a similar problem when I first apply a head-kit to a mainboard! It usually locks-up right as it gets to the POST screen! I just leave it for 24 hours and it works fine!

 

[mjh74]

Thanks for that offer Phil.

Interesting update. Thought I would leave the prommie/machine on all day to see what happened. The machine initially booted up with the evap temp at -53c, CPU full load of -7c. Left things running whilst I was at work and when I got back the display was reading -43c and the machine was dead. I tried to get the machine to power on again with no luck but 1 attempt where it froze at POST. I removed the power and let the prommie temp climb back into + temps and removed the motherboard ready to strip off the CPU kit to check for condensation. Prior to putting it all back together this time, I had coated the back of the board behind the CPU with silicone sealant and also around the CPU on the top of the board, filled all CPU socket holes with dielectric grease and in the centre then applied 2 layers of seal string. The last step was to degrease around the socket before applying the kit. I removed the 4 screws and started "the battle against man and sealant". Degreasing the board made this stuff stick like never before! After I'd managed to pry both sides off, I very carefully inspected where the 2 layers of string had been, there wasn't even the minutest of gaps, even around the top of the CPU where the string sits on a mosfet and some surface mount resistors, nor a damp patch/drop of condensation in sight. Not that there was any space between the string and silicone sealant to really get any condensation! I re-applied a standard heatsink and fan to the machine, all powered up first time and has been under full (2 sessions of prime95 running) load for 20.17 hours now without a single glitch. Needless to say I am totally confused. I can't see why the prommie could be at fault as thats still powered on and at minus temps when the board stops working .