ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

[dicky96]

Guys I don't have much experience at all with modern motherboards so I may ask a few dumb questions here

I have this Z270 Mk 2

If I power it up with no RAM it beeps as you would expect and the RAM LED (orange) lights up constantly

If I power it up with 1 or 2 DDR 4 fitted as according to the user manual it does not beep and I get no output from the onboard graphics or a PCIe GPU (GTX 750)

I have a PCIe POST card (one of the bluetooth type) but I have almost tried it before apart from testing that it does work on a known good board.
https://www.aliexpress.com/item/3239...archweb201603_

I get no POST code with it in any PCIe slot

I have Vcore to the CPU 1.028V
I have Vram 1.24V
I have 3.33V and 1.024V on the capacitors integrated to the top of the North Bridge

all that looks good.

Known good compatible Celeron G3900 CPU and all pins in the LGA1151 socket look good under a microscope

Nothing is getting hot and no visible damage

Tested with No RAM, with pair of Corsair Vengeance LPC 2400MHz DIMMS and also with single DIMM in any slot.

The result is always the same with the diagnostic card in any PCIe slot, I get 'Did not receive the QiGuan open code of the PCIE slot'.

When I power on with RAM fitted, the orange RAM LED comes on for a few seconds and goes off. If I press the MEM TEST button and hold it down when the orange LED is on then it goes through the motions of trying different RAM settings as described in the user manual - powers off/on every 30 seconds or so and I get different 'flash codes' on the orange RAM LED but eventually it goes back to the first stage, RAM LED lights for a few seconds then goes out.

There is a little 9 pin connector (marked with red arrow in pics) and this is not mentioned in the user manual. I thought perhaps it is an LPC debug port but when I connect my diagnostic card to that (tried various orientations) the board will power on (with or without RAM) but no longer beeps without RAM

Why do I get no POST diagnostic code when the motherboard it is obviously active?

Do these sort of boards output the POST codes in some other way than to the PCIe slot?

Can these modern boards be really finicky with DDR4 RAM type? The ones I have are known good, as is the CPU and the speed of the DDR4 (2400MHz) should be compatible with this board according to google search but could that be the problem.

Pics attached

[bartx]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

I'm not 100% sure, but this 9-pin connector may be the interface for bios flash. Is there a bios IC near this connector?

Does this board have a bios flashback? It allows to flash the bios without even powering the board.

[piernov]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

PCIe POST debug cards are mostly useless. Use the TPM header instead, that's an LPC bus header where you can connect the POST debug card.

The 9 pin header indeed looks like an SPI header to flash the BIOS in-circuit (but I rarely have luck doing so, so I always take the SPI ROM chip out). It is right next to an SPI ROM that probably contains the BIOS.
And yes that could be a corrupt BIOS. Double check it's indeed not POSTing, for example checking that caps lock key doesn't trigger caps lock LED on a USB keyboard.

[dicky96]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

I removed the BIOS and programmed it with this file from ASUS website

https://www.asus.com/us/Motherboards...HelpDesk_BIOS/

The file wasn't a BIN or ROM file it said it was a CAP file, whatever that is but my PC said it was the same size (16Mb) as the backup I made of the original ROM before erasing it, and the programmer happily wrote it to the ROM and verified it/.

Anyway once I wrote that to the BIOS the motherboard would not boot - it would start and the CPU light came on solid Red but it no longer flashed the orange RAM LED or beeped with no RAM fitted

I had a look the the backup file and the one I downloaded with a hex editor and figured out the downloaded file had some Kilobytes of shite at the start of it. So I edited the file to remove that and then programmed the Bios again with the edited file.

There are some differences between the edited download and the original file.

Now it boots again and beeps with no RAM fitted but it still doesn't boot or beep with RAM (I get no video output). I checked the Caps Lock LED on a USB keyboard, it does not illuminate either so I can say for sure the board is not fully booting once RAM is fitted.

As before, if I press the MEM OK button the board goes through the sequence of testing different RAM settings as described in the user manual.

That little 9 pin connector I found near the BIOS does in fact connect to the BIOS pins. So where do I find this TPM header to attach a POST test card to get some better idea what is going on with this?

Rich

[piernov]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

CAP files are UEFI Capsule, you can use UEFI Tool to extract the BIOS image rather than fiddling with hex editor.
The TPM header should be indicated in the motherboard manual. If it's not, then chances are it doesn't have one unfortunately.

[dicky96]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

Yes it does have a TPM header, it shows it in the user manual.

I should correct something I said in my previous post:

I meant to say

Now it boots and beeps with no RAM fitted and it boots but doesn't beep with RAM (I get no video output). I checked the Caps Lock LED on a USB keyboard, it does not illuminate either so I can say for sure the board is not fully booting once RAM is fitted.

As before, if I press the MEM OK button the board goes through the sequence of testing different RAM settings as described in the user manual.

[dicky96]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

I connected the USB keyboard and connected the POST analyzer to the TPM header.

According to the manual with POST card it says it has an auto detect feature and you can connect it to TPM in either orientation and it will work. I tried it both ways and it does not. I still get the same message as before, 'Did not receive the QiGuan open code of the PCIE slot'.

It also says if there is no POST from the TPM to contact tech support for the analyzer with details of the motherboard as it (the analyzer) may need a firmware update. I did that a couple of days ago, I'm waiting a reply.

With the USB keyboard I get no Caps Lock LED so it is not booting all the way, though it will execute the MEM OK! test sequence by pushing the test button as the user manual says so the CPU must be active and running the BIOS program.

I just don't know at what point it stops POSTing so how can I diagnose this further?.

It doesn't crash as such. I can run MEM OK! test sequence again without restarting it.

Rich

[dicky96]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

OK so I contacted the tech support for the PCIe / LPC post diagnostic card as to why I get no POST data from this motherboard

Basically they suggested I have a chipset fault.

It's obvious the motherboard does power up and the CPU must be running and is able to execute BIOS code, as it goes through the test sequence when I press the MEM OK button (restarts several times and flashes different codes on the RAM LED)

I've used the same RAM and CPU on some other boards I've been working on this last couple of weeks including an Asus Prime Z270-P and that is working now and it's the same chipset. So I have to assume that the RAM and CPU are good and also compatible,

I'm at a loss to work out further what is going on here

Rich

[SMDFlea]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

Can you try this bios .

[dicky96]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

Sure mate, I will try it on Monday

A couple of days ago I tried my PCIe diagnostic card on the working Asus Prime Z270-P board with the same chipset - and I don't get any POST codes on that either, at least not on any of the PCIe slots - it didn't have an LPC connector unless i missed it..

[dicky96]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

@SMDFlea
I tried that bios but it does not make any difference

It still beeps with no RAM and goes through the test sequence with RAM if I press the Mem OK button. I tried with 2 DIMMs fitted and with one fitted. I tried all combinations A1/B1 A2/B2 and each slot individually

After it tries 3 different reboots, it comes on and stays on but doesn't boot

[dicky96]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

I thought it would be a good idea to probe around the TPM header to see if there was any activity there when the board is doing its MEM OK test

All i found is pin 14 is 0V, and all the others are 3.3V apart pin 5 which has a high frequency clock on it with a duration of around 0.04uS (around 25MHz) according to what I can see on my trusty old 465B scope

So there seems to be no data there for a debug card to read, unless there is a quick burst of data at power on, and I am missing it.

[piernov]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

I've had no problem using the TPM header for POST debug codes with the TL460s Plus card on several MSI, Asrock, Asus… boards. Closest one to yours is an Asus Prime Z270M-PLUS.

[dicky96]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

Yes I think part of the problem is my PCI-e/LPC post test card is shite.

I was thinking of getting this one instead - TL611 Pro
https://www.aliexpress.com/item/4000...c-b2104c2e395a

It seems that is an upgrade or replacement of the TL460S Plus whci doesn't look like it's available any more?

[dicky96]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

I had another look at this
I now have A TL460S Plus POST Analyzer. I'm also using a different test CPU (i3-6100) and different ram Vengeance LPX 2133GHz 2x4Gb

With No DIMMs fitted I get DRAM LED on TL460, code 53 and it bleeps.

With one DIMM in either A1 or A2 slots I get no beeps, the LEDS on the TL460 flick on/off then finally settle with VGA LED illuminated and code 0A. I get the same with 2 DIMMS in A1+A2.

With one DIMM in B1 or B2 I get no LEDS lit on the TL460 and code FF

With two DIMMs in A1+B1 or A2+B2 I get no LEDS on the TL460 and code FF

So maybe possibly I have a problem with ram channel B1/B2 but that would not explain why I get the VGA error with a single DIMM in A1 or A2 or two in A!+A2

[re-atari]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

Check the 'Motherboard Pinout' section on this page for more info on the TPM and LPC Debug connectors pinout:
https://elmorlabs.com/index.php/2018...pc-debug-card/

Note that POST cards have their peculiarities. I received my TL611Pro last weekend, tinkered a bit with it, mostly just to decypher the Chinenglish user manual.
At first I feared the card I received was defective, as it didn't do anything in the PCIe slots on my (fully functional) MSI X370 mainboard. It turned out on MSI boards the POST card only works properly if inserted in the TPM connector. On Gigabyte boards you have to use one of the PCIe slot.
It took a bit of imagination to conclude that this was what the 'user manual' meant to say.
Ah, the blessings of clearly written documentation...

[dicky96]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

@re-atari
the TL460S seems to be working OK on the TPM as far as I can tell. It is giving me POST codes. I get the VGA error LED using the onboard DVI connection. I also tried an old graphics card but it may not be supported by UEFI BIOS so I am going to try again with a know good GTX 960 after the weekend

[re-atari]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

I reread the entire thread, and now see what you mean. Looks like a very annoying error, that gives seemingly unlogical error codes/leds. Hopefully another PCIe VGA card will give a display, but it will probably have to contain an UEFI VGA bios to work on the mainboard. If this isn't the case you could circumvent this in the mainboard's UEFI BIOS settings (turn on legacy), but the catch-22 is that you first have to have a working mainboard to do so.

I have something similar here, a MSI made Medion mainboard (MS-7797, socket 1155) with known good CPU and RAM, no bent pins on socket, but refusing to properly start up. CPU (Celeron G1610) gets warm, but no display or beep from built in piezobeeper. A PCIe VGA card won't give a display either.
The mainboard has a TPM socket, so I should really give it another go with my TL611 inserted, but sadly other more important things to do ATM.

[dicky96]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

I was using this motherboard yesterday to make a youtube video (simulated high side MosFET short on Vcore) and I spotted one pin in the LGA socket looked a little out of line

After the video I had a look at that and thought it could just possibly be shorting to the next pin when the CPU was in place so I straightened it.

I now think that RAM Channel 2 of the DDR sockets is working because I get the same error code on the TL460s with a single DIMM in A2 or a pair of DIMMs in A2+B2

So that is an improvement. I am now getting error A0 and the VGA LED lit on the TL460 regardless of the RAM configuration. Interestingly, the VGA diagnostic LED integrated on the motherboard does not light.

I have now tried using the onboard DVI connector, and two know good graphics cards, a GTX280 and a GTX960 in the PCIe slot nearest the CPU but I always get A0 and no picture

I had a very close look for more bent pins but really could not find any.

My POST analyzer came without any documentation. Does anyone have a user manual, I did google but couldn't find any free sites that have it.

Otherwise does anyone know what A0 means in UEFI BIOS?

[re-atari]

Re: ASUS TUF Z270 Mk 2 beeps with no ram but will not boot

Although the attached document is about another manufacturer's mainboards, the list of AMI POST codes and their meaning just might be helpful in your efforts to fix this ASUS board.

BTW: I have subscribed to your YT channel some time ago, and was watching video #67 about fixing a supposedly 500W PSU earlier this evening. Noticed the 2 IC layout, immediately suspected they will be a TL494 and a LM339. Turned out to be correct.
The KA7500 is compatible to a TL494, your PSU's silkscreen even shows a TL494 is supposed to be installed there. TL494 and LM339 should both be readily available in electronics components shops.