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**socketa** · 01-12-2023, 08:14 PM

Re: NF4UK8AA - Is this Lazarus, just sleeping?

Now i can't power down the board with the power button.
It's got worse without me doing anything.

Still get error 44
When i hold down the power button the reset LED on the analyser card lights up (after several seconds, like normal), but stays lit when i release the button.
The only way to power down the board is by turning off the PSU.
What could this indicate?

It's like a chip is recognizing that i held down the power button, but it's not passing it on
Maybe is a bad nVidia NF4 chip? (i seem to recall that they are part of nVidia bumpgate)
Odd how it went from sometimes reaching BIOS config and freezing, to working perfectly, to not even getting to the point where is detects missing RAM/RAM in wrong slot and not being able to be be powered off
It's like some stories that you hear when folk are on their death bed, where for a brief period they sit up and become very conscious, then a few minutes later they're dead (so to speak)

**DynaxSC** · 01-15-2023, 03:44 AM

Re: NF4UK8AA - Is this Lazarus, just sleeping?

What agent did you use to wash the board?

**socketa** · 01-15-2023, 02:32 PM

Re: NF4UK8AA - Is this Lazarus, just sleeping?

I used about a tablespoon of dishwashing liquid in about 7 litres of hot water with a soft toothbrush, (photo attached),
then gave it a rinse in another container of hot water.
Prior to removing the MOSFETS, there was one time where i could power down the board simply by gently tapping it with my finger (yes, the ATX connectors were fully plugged in) - tried it a few times, and could repeat it; but it didn't happen again after that - i did try flexing the board to see if that made any difference when starting, but no.

Attached Files

**momaka** · 01-16-2023, 06:08 PM

Re: NF4UK8AA - Is this Lazarus, just sleeping?

It's an nVidia chipset board... and a socket 939 at that... so I probably need not say more. (But I always do.

)

Yes, the nForce 4 is affected or at least partially-affected by the bumpgate issue. In fact, I have one Biostar board that's acting similar to yours - sometimes it boots, other times no. It still boots more often than it doesn't. But I'm sure it will get worse.

The stock heatsinks on socket 939 also had a tendency to warp the board very badly, so the issue could be bad BGA under the CPU socket too.

That said, I'm willing to bet my money on a bad/dying nForce chipset.
Before you go nuts with the heatgun, though... try booting the board with the CPU heatsink on the CPU, but with the retention spring loose. Any difference?

Also, is the thermal paste on the nForce chipset's heatsink good? Tried replacing it? If not, try that too.

And if it still misbehaves, give it heat from hell... er, I mean the heat gun.

You may not need to reflow it to full RoHS solder melting temperatures to get good results. 150-180C on the chip could be enough. But if not, do it again and crank it up more.

BTW, if a board is turning On and not shutting down instantly, then there's no need to mess with any of the MOSFETs. A shorted MOSFET will either make the PSU shut down right away or it would be overheating and causing serious discoloration/burn marks on the board. So if you're dealing with an intermittent issue, the problem will almost never be a bad MOSFET.

**socketa** · 01-16-2023, 09:12 PM

Re: NF4UK8AA - Is this Lazarus, just sleeping?

Ok, thanks
Yeah, i did all of that
Blasting it is a last resort - thanks for the tips though, in case it comes to that.
While looking over the area again, i noticed a bulged driver
Now, i don't know it it was like this when i got the board, or if it was a consequence of spending too long heating the MOSFETs when removing and replacing them (i only had the hot air gun on the MOSFETs)
So i'll order another one and another MOSFET, and hopefully replace them without destroying any other components.
Could a damaged VRM driver be a reason why the board is faulting?
Also when i got the board i noticed that the NB driver fan was noisy/erratic, and had being replaced, and that the third wire was disconnected (which i reconnected, and the BIOS health screen showed that it was monitoring it's RPMs, and also spins lot quieter now) - So the NB may have being running without a fan for some time.
The fan makes a big difference to the NB temperature - from being fairly hot when it's not connected, to being luke warm when it is.

Attached Files

**momaka** · 01-16-2023, 10:47 PM

Re: NF4UK8AA - Is this Lazarus, just sleeping?

Originally posted by socketa View Post

While looking over the area again, i noticed a bulged driver
Now, i don't know it it was like this when i got the board, or if it was a consequence of spending too long heating the MOSFETS when removing and replacing them (probably the latter)
So i'll order another one and another MOSFET and hopefully replace them without destroying any other components.

What soldering tools are you using to replace the MOSFETs and drivers? Hot air?

The VRM area is pretty hard to heat, so it's definitely possible the driver IC could have been heat-damaged from the hot air.

I myself prefer using just two soldering irons to remove such parts and save the hot air only for TSSOP or finer pitch ICs. In case of MOSFETs, I use my 75W station to heat the tab, and then a 30W iron alternating between the two legs. Once all heated, I slide the MOSFET away. Same with 8-pin ICs, like that driver. Takes only a few seconds to remove a MOSFET that way and there is minimal heat leakage to any other components. Before doing any of that of course, I first add fresh solder to the tab and legs of the MOSFET. And in the case of 8-pin SO/SOIC, I add solder to bridge all of the pins on each side.

Originally posted by socketa View Post

Could a damaged driver be a reason why the board is faulting?

Unlikely, but I won't say no.
If the driver IC is bad in such a way that it's not shorted and also not doing anything else in the circuit (i.e. not driving the MOSFETs at all), then that phase in the VRM won't be contributing its share of providing power to the CPU, and so the other two phases will have to work harder. And since phases are usually staggered on multi-phase motherboards, one phase missing can cause the ripple current and noise to increase significantly. If that's the case, then that could well be why the motherboard is crashing. But more often than not, a bad driver IC typically causes one of the MOSFETs to get stuck, and then the whole VRM tanks and doesn't work and/or PSU goes into protection from overload due to "stuck" MOSFET.

Originally posted by socketa View Post

Also when i got the board i noticed that the NB driver fan was noisy/erratic, and had being replaced, and that the third wire was disconnected (which i reconnected, and the BIOS health screen showed that it was monitoring it's RPMs, and also spins lot quieter now) - So the NB may have being running without a fan for some time.
The fan makes a big difference to the NB temperature - from fairly hot when it's not connected, to comfortable when it is.

Yeah, my Biostar NF4U AM2G was in a similar condition - NB fan was very noisy and possibly may have been stuck for a while before the seller / previous owner cleaned it to get it running. It's still very noisy (BB's are shot and make "sand grinding" noises every once in a while.)

I also had an ECS MCP61PM-AM recently die on me. But it's been on a deathbed since 2018, so not like it was unexpected. Would die, then I'd get mad at it and punch the chipset heatsink (literally!

), and back to working for a few more months. It has a GeForce 6100/6150 chipset. If you ever run into a board with one of those, AVOID IT by all means. I didn't believe it, but these things are definitely all doomed to fail. In the case of the above board, the LAN started going out back in 2014 (and probably why I found that PC in a dumpster.) Gotta take it out of the PC one day and do a reflow. Maybe that will buy it a few more years. CPU's a X2 6000+, which holds up surprisingly well even today.

**Dan81** · 01-17-2023, 12:17 PM

Re: NF4UK8AA - Is this Lazarus, just sleeping?

Got a NF4UK8AA as well, mine boiled down to the weirdest thing ever:

-won't boot with its own BIOS freshly flashed on a blank chip.
-will successfully POST with a DFI NF4 SLi INFINITY BIOS chip.

Anyone have any ideas what the actual ever living bejeezus is going on with this mobo? I've tried flashing the BIOS over at least two mobos (an ASUS P5PE-VM and the above-mentioned DFI) and the same result happens.

To recap what I tried:

- two BIOS chips - one is the original SST 49FL004B chip, the other a PMC/PMIC Pm49FL004T-33JCE - both won't POST on the Winfast NF4UK8AA, but will work if I put them on the DFI mobo
- various RAM sticks - even as far as using ADATA Vitesta DDR500 sticks (as they came with the Winfast mobo, along with a pair of 2x1GB Kingmax sticks) to no avail - none will work with the Winfast BIOS, but will work fine with the DFI BIOS.

**socketa** · 01-17-2023, 11:56 PM

Re: NF4UK8AA - Is this Lazarus, just sleeping?

Yeah, i used a hot air station.
Thanks for providing a better technique/alternative
That "bulged driver chip" now appears to be a good chip with a coating of flux on top of it (i realized that after measuring all of the pins to ground, and they all were the same)
So, i cleaned it up, plugged the two ATX connectors back in, pushed the power button, and now get horizontal dashes on the POST analyser card. (which is what happens if i forget to plug in the 4-pin CPU ATX connector)
So then i check the voltage of Vcore, and it's 1.01V, which is significantly less than what it was before. The drain pin is 11.94V.
I didn't do anything, except wipe the flux off of the top of the chip. Now i turn it back on, and Vcore has dropped to 1.01V

**momaka** · 01-18-2023, 08:25 PM

Re: NF4UK8AA - Is this Lazarus, just sleeping?

In the CPU is constantly resetting due to something being buggered with the chipset, that could be the reason why you see the low voltage on V_core.

Given how it's been slowly going downhill, it might really be time to flow the nVidia chipset... unless you have a programmer and can do what Dan81 did and flash a different ROM on there (after backing up the original, of course.)

BTW, have you tried removing and installing the CPU a few times? I've had issues before where a system slowly became more and more crash-prone until it stopped booting. Turns out the CPU pins had the slightest bit of oxidation where I touched them on the side, and that caused the board not to boot. Some cleaning + a reinstall of the CPU in the socket, and it was back up and running.

**socketa** · 01-19-2023, 12:12 AM

Re: NF4UK8AA - Is this Lazarus, just sleeping?

I tried a different CPU, an Athon 3000, and this one went to POST code 44 (again) with Vcore at 1.01V
Thought that i must have destroyed the 3200 CPU that i was using, after reinserting quite a few times previously,
so i mucked around trying to bend the pins, with a meter probe, that looked a bit off (wound up bending one right over in the process), until i thought that using a credit card would be a much better/safer way to align them....
Put it back in, but still just horizontal dashes on the analyser card
Tried a 3500 CPU but still horizontal dashes again
Tried reseating these CPU's many times - same result
Thought that it was a bit odd that two CPU's would be buggered, or that the socket would be so fussy (all of the contacts look good when moving the CPU lever under the microscope), so tried all three CPU's in another board, and that board POSTed no problem

Could it be that there is power issue that is preventing the board from starting up, as there is enough voltage at 1.01V to just start the POST process with a 3000 CPU, but not the 3200 or the 3500 CPUs?
Vcore on the other board is 1.4V
So i suspect that that is what's halting the boot process, because, with the 3000 CPU, the board is obviously POSTing, but it's getting stuck at a certain point in the process because of low Vcore.
It really looks like 1.01V is not enough voltage to to allow the POST to fully complete.
The code 44 (Phoenix) says "Initialize BIOS interrupts.(Beep)=2-1-2-1. Verify video configuration." so i'm thinking that whatever that is, something changes at that point, and then there's not power to continue with the boot sequence. (just thinking out loud)

As previously mentioned, for some reason the board was working no problems, after i removed and put back MOSFETS; then as soon as i put that video card in, and restarted, something changed:
Maybe the video card did a bad thing to the motherboard, or maybe that was just coincidence...
or maybe there is something dicky going on with the VRM on the board (it's not the PSU - i tried another good one just in case it was) because a couple of times there was no response when i pushed the power button, and another time i could power off the board simply by tapping the corner of the board.
Anyway, i think that the issue at hand is the fact that Vcore at 1.01V is just enough to perform some of the POST with an Athlon 3000, but not enough to complete it.
Any thoughts on how to approach troubleshooting that?

**momaka** · 01-19-2023, 12:54 AM

Re: NF4UK8AA - Is this Lazarus, just sleeping?

If the board worked before you messed with the VRM... or at least POSTed every once in a while... then perhaps you did something to the VRM area that's causing the low V_core now.
My suggestion is to first check the voltage feedback network going to the VRM controller. Get a datasheet for the VRM controller and see which/where is the Feedback pin. Then run back from there and see if the resistors that connect this pin to V_core and ground have proper values. The VRM controller is also likely receiving I2C data either from CPU or BIOS for the voltage control. So bad BIOS / CMOS data could lead to wrong CPU voltage. Same with the feedback resistors on the VRM controller.

Also, while I do usually suggest to remove and reinstall CPU(s), I also suggest not to do it too many times. CPU sockets aren't meant for too many connect/disconnect cycles. IIRC, it was in a tech note for Intel LGA socket, and said that the number of guaranteed connect/disconnect cycles was only something like 6 or 7 (i.e. only 6-7 CPU changes.) AMD sockets might be able to take more... but who knows.

So while a good idea to try different CPUs, also a good idea not to overdo it. If I have 2 known good CPUs and one doesn't work, I will try the other one. If that doesn't work too, then I don't bother swapping CPUs anymore.

It's also very rare and hard for a mobo to kill a CPU, especially the older CPUs. I've had a particular LGA775 CPU for example, survive 5 direct high-side shorted MOSFETs.

**socketa** · 01-19-2023, 07:56 PM

Re: NF4UK8AA - Is this Lazarus, just sleeping?

Without the CPU there is 46 ohms from controller feedback pin to Vcc.
With the CPU there is a hard short from controller feedback to Vcc
Couldn't find a schematic for this board, but i found one for a similar board
Attached, is the schematic (NF3UK8MA - same controller, drivers, and MOSFETS)
Then, i calculated (from the schematic) the equivalent resistance of the series/parallel resistors that are between feedback and Vcc, and got 46 ohms
So, unfortunately, that appears to be OK

Attached Files

**socketa** · 01-09-2024, 04:59 PM

I flashed the bios, but still get code 44 on the PCI slot card
the only noticeable difference is that the board now powers down when the power button is pressed,
1.02V VCORE sounds too low to me

...A few hours later , now a hard short has developed across VRM mosfets
...Found, and replaced, the shorted mosfet, and it shorted again as soon as power was applied
...Replaced that one, and now get code D0, and now can't shut down with the power button - VCORE still 1.02V
Am wondering that since i replaced the mosfet with a different brand, maybe i should replace all of the other paralleled mosfets, so as to make them all exactly the same?
Maybe that's what causing the low voltage?

... replaced the other mosfets so that they all match, but that made no difference
...maybe the bios got corrupted when the VRM shorted
...will try re-flashing it

**прямо** · 01-09-2024, 05:51 PM

According to the controller datasheet, VCORE is set by VID0...VID4 and on the schematic, these pins are directly connected to the CPU socket.

Perhaps you can compare their states (high or low) with this table,

and instead of injecting 1.5V directly into VCORE, I'd force these pins to match what the table says for 1.5V

**socketa** · 01-10-2024, 08:01 PM

Thanks for that
Re-flashing made no difference
Am assuming that i should be looking at the K-8 output voltage chart that's on that datasheet, since the CPU is AMD socket 939
On VID pins 0 to 4 there is 10110 (3V = high),
and that equates to 1.00V

Meter shows about 1.0V
Shorted a few of those pins to ground and had it up to 1.2V and the PCI card moved on to a different code and stopped there
But now i noticed that the mosfets were getting hot, Vcore 800mA, and now the CPU is shorted
Maybe i briefly put it up to 1.55V, and killed the 3000 CPU since it's maximum specified voltage is 1.35/1.4V
If that's true, i wasn't aware that an extra 0.15V could kill a CPU
I've now put a 3200 CPU into it, but of course there's not enough voltage to fully power the CPU 1.35/1.4V
It's still 10110 (1.00V)

00110 would be 1.4V

VID4 is 2.77V when the other two highs are 3.0V
It's a bit suspicious
Maybe there is a faulty component in the VID4 circuit that is stopping it from being pulled low,
because 00110 is only one digit different from 10110

Hmmm
If the VID signals are generated from the CPU, then it seems that the CPU is asking for 1.4V, but it's not getting it, so it's not POSTing.
At the moment i'm not keen enough to ground VID4 in case doing so kills this CPU also

**прямо** · 01-11-2024, 09:33 PM

It doesn't make sense to me that when it's being forced to pull low, it will end up overheating the mosfets and killing the CPU, because these pins are supposed to change states real-time, in respond to whatever voltage the CPU requested, such as when a user is under/over-volting the CPU on the fly.

Most likely what killed the CPU was the high side mosfets gate were opened and 12V passed through.

Other than pull up resistors, I don't see any additional circuitry. Pins are direct connection from the CPU to the phase controller and shared with super IO for monitoring.

Maybe try turning on the mainboard without a CPU and see if the VID pins change state accordingly (all pulled low = OFF)

The alternative of injecting VCORE from your bench supply poses a much higher risk factor because it involves exposing the components to an excessive heat from your hot air blower gun, since you will have to remove the mosfets and then force the phase controller to stop working (either by pulling VID pins to low or remove the chip)

**socketa** · 01-12-2024, 03:22 AM

Yeah, maybe the 3000 CPU was just about dead after the upper vrm shorted,
and it had enough life in it to to POST, but then fully died

This board also has an IT8206R "jumper free overclock controller" that's located next to the VRM controller, and VID 0-4 also go to it

There's five 4.7k pull up resistors
with the PSU and CPU removed, they all measure 3.4kohms in-circuit,
except for VID3's resistor, which is 1.3K

With the CPU removed, there is 1.0v VCORE, which corresponds to what's on VID 0-4 10110
With the CPU installed, there is 0.975 VCORE which corresponds to what's on VID 0-4 10111

OK, so i felt confident to start it up while shorting VID3 to ground
which put 1.370V (probably 1.375V) on the VCORE, and code 45 on the pci card,
but still couldn't swtich it off with the power button

And it obviously didn't like it, becuase now the VRM is not being switched (no voltage on the mosfet gates), so nothing on VCORE
i checked the CPU - fortunately, it's VCORE isn't shorted to it's ground like the other one.

Tried resetting the bios, but no change

Was reading that resistors don't usually fail short, so the pull up resistors are probably OK
Am thinking that that out-of-line reading across VID3 pull up resistor is possibly an indication of a faulty controller chip

**прямо** · 01-12-2024, 04:24 AM

Try pulling VID3 low again, but without a CPU this time, and see if you will actually get 1.37V or not, because I don't think the phase controller chip is faulty, after all it was able to put out the correct voltage for 0.975V, 1.0V and your earliest attempt at 1.2V

**socketa** · 01-12-2024, 02:47 PM

Did that (sorry, it was VID4, not VID3, that i pulled low to get 1.375V)
There's 12V on the three drivers supply pins
There's 8.57V - 8.64V on the low side gates,
but there's no voltage on the high side gates,
and of course, there's no VCORE

The controller is putting out a signal 10110 (1V)
and when grounding VID4, there is still no VCORE, since there's no voltage on the high side gates

There is no voltage on the PWM OUT pins

Then i accidentally shorted OUT1 to AGND, and it shut down, now the board wont start
It tries to start (nForce4 fan twitches), and shuts down nearly instantly because the high side mosfet's drain and source are shorted to each other

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NF4UK8AA - Is this Lazarus, just sleeping?

NF4UK8AA - Is this Lazarus, just sleeping?

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