NF3 250GB Cold Boot Problem

[ztech1]

Hey Spartacus,

While I’m not out to hijack this thread and would rather not take the time to debate electrical theory with you I feel I must make a few things clear.

First,

While I know the difference between a warm boot (boot with the reset switch) and a cold boot(boot with the power switch) the particular problem I had as well as Alice_in_Chains and many others is the system would need to cool down for a period of time to repeat the detection error. Powering off the system and restarting it immediately would allow a normal startup because it’s still “warm” although it’s technically a “cold boot”.

So “temperature” has everything to do with the original problem in this thread.

 

Your figures from Antec are for the AC side of the PSU. There is a large capacitor(s) that store power for the PSU’s sag resistance. This is the ability of the PSU to continue to deliver the proper DC voltages even if the AC input drops due to factors associated with the home wiring load or the power grid itself. The large starting current draw you quoted is for charging the PSU’s capacitors. These have nothing to do with the load the motherboard is imposing on the DC side of the PSU. My quote on the “surge current” was derived from measuring voltage drops across the DC rails using a graphing DVM while starting the system. I also have a clamp type ammeter but with no graphing function. My particular 250GB didn’t show much of a voltage drop or current spike during startup so that’s where the 5% came from. It’s not really relevant to the problem as the detection issue would occur with both the power switch and the reset switch.

 

The only reason I originally posted in this thread is I had a similar problem that I had fixed and I’m not really fond of some of the “shotgun” troubleshooting that goes on here. It’s never been proven that the PSU causes the original detection problem so I personally can’t see recommending someone change it in an attempt to fix the problem although I’m sure weak PSU’s can cause plenty of other system problems.

I’ll leave it at that – have a good one .

[Guest Spartacus]

Hey ztech,

 

I agree we should not hijack the thread with back and forth banter.

 

I think we are actually helping in that we are talking about the problem and it's possible causes. Hopefully we can all learn something and hopefully find a fix for the problem by kicking around some ideas.

 

My take on the problem is not that the temp is the difference, but that the PSU was recently powered up. The big caps bleed down slowly over time. This means that the caps are partially charged if you turn off the system and then turn it back on again within minutes. That also means that the surge current is not nearly as severe as it would be if you waited hours to power on the system again. By that time the caps would be fully discharged. A re-powered PSU will come up to stability much more quickly than a dead cold one.

 

I think what can happen is that the PSU has not yet stabilized by the time the CPU is running and is beginning to POST and boot up the system. Any power fluctuations during this time can induce errors and erratic behavior.

 

Put another way, it's actually a timing problem. The system is trying to POST/boot but the PSU is not ready yet. There is a signal called the "power good" signal that is raised high by the PSU when it THINKS it's ready. There is logic on the mobo that keeps RESET low until it sees PG go high. I'm not positive on the logic states (high vs. low) but that's the general mechanism. This is SUPPOSED to keep the mobo from running until the power is stable.

 

This mechanism has worked well for a long time, but I think new high-powered systems are pulling a lot more power than they used to and this is causing some dynamics that up until recently have not been a problem. We didn't used to have all of these no POST and cold boot issues going back a few years.

 

All of this can be made worse, by overloading the PSU or starting out with a poor quality PSU. What if the el-cheapo PSU makers don't actually design reliable power good logic, but they just use a timer to raise PG after a set time? This may work MOST of the time. That is until you go to hook up your new high-powered DFI mobo.

 

It could also be a design issue on the mobo or chipset. I've also seen cases where parts from different vendors just don't work together. You can take either part, put it in another system and it will run fine. But try putting the two parts together and they don't work. These compatibility problems are caused by timing or power issues usually.

 

I can think of a way to test this if anybody is interested....

 

Disconnect the PSU from the mobo so that it is not getting any power and will not have any temp changes on the chipset or other components. Then power up the PSU by jumping out the right pins as noted here: http://www.duxcw.com/faq/ps/ps4.htm

 

Let the PSU run for a minute or two and then shut it down.

 

Reconnect the ATX power connectors and then power up the system normally. Be sure to note any hangs/problems or if the system comes up normally.

 

If anybody tries this plese be careful, I don't want to see you smoke anything. I have powered up PSUs like this myself and never had a problem, but I take no responsibilty for anything "bad" that may happen from this test.

 

If somebody with this cold boot problem can try this, please let us know what happens.

 

EDIT: BTW, I would never advise anybody to keep running out and buying new parts either. Finding and fixing problems is always better than shot-gunning. If you already have the spare parts though, shot-gunning can be a very quick and easy way to narrow down the problem.

[cyberfossil]

for the heck of it try enabling spread spectrum.

[Alice_In_Chains]

Another odd thing is that it will stop at different areas of POST not just one. Its a random problem which doesnt make any sense.

[Alice_In_Chains]

Could someone explain spread spectrums pros and cons

[cyberfossil]

I read this over at the XtremeSystems forum and it was posted by Oskar Wu the designer of the board. I don't know if it applies but who knows

 

http://www.xtremesystems.org/forums/showth...&threadid=41798

[Alice_In_Chains]

Very good information. My opinion is regarding bootup there should be no problems when not overclocked(With the understanding that everything is hooked up properly). If I where overclocking and this was a result of that I would not even be posting here. I don't understand why I am having this problem running stock. I would hope that this is not normal. I know its not. I am thinking that this may require a return. I wonder how long that process takes? I really love this board other than this one problem.

[cyberfossil]

have you tried cranking up the ram voltage? the cpu voltage?chipset voltage?

[Alice_In_Chains]

All of that sounds great but on a stock board hooked up properly with appropriate equipment this should not be necessary. I thank you for your help but cranking up voltage isn't an option.

[cyberfossil]

if you are gonna return it anyway what do you have to loose?

[Alice_In_Chains]

I understand what you are saying. I was just thinking that having to do that just to get the board to work normal isnt right. I mean it may help but my point is it shouldnt have to be done.

[M4d-K10wN]

My mobo doesn't like to do cold boots either. Comes to think of it, my K8N Neo Platinum often didn't boot cold too... methinks it's a problem with nF3 250 chipset.