Asus P5P43TD won't boot or beep with memory fitted

[dicky96]

Hi guys
I have this ASUS P5P43TD motherboard. If I boot with no RAM and no VGA card fitted it stops on POST code D3 and beep 1 long + two short, repeating.

But if I fit some DDR3 it stops with POST code F0 or 40 and does not beep at all. Generally if I fit 1 DIMM in slot A1 it gives error F0 and if I fit 2 DIMMS it gives error 40

It has an AMI Bios. According to my POST analyzer, 40 means 'preparing the descriptor tables next' and F0 means 'next, searching for the AMIBOOT.ROM file in the root directory'

F1 would mean 'the AMIBOOT.ROM file is not in he root directory' but it never goes past F0

I reprogrammed the BIOS with this one from the ASUS website https://www.asus.com/us/Motherboards...HelpDesk_BIOS/ but it makes no difference.

I tried various DDR3 single or as pairs 1GB, 2GB, 4GB, PC3-12800U, PC3-10600U, PC3-8500U, - no difference

I have 1.3V Vcore and I have 1.5V on VDD on the DIMM and can also see 0.75V on some capacitors on the DIMM so that would be VRef?

All looks good but it don't work.

Any suggestions?

[dicky96]

Re: Asus P5P43TD won't boot or beep with memory fitted

I looked up the meaning of those error codes and they are apparently related to the processor switching from real mode to protected mode.

Having read somewhere that the Super IO (W83627DHG-A) switches the modes I had a look and it was covered in nasty looking corrosion on one side, though this was not that obvious until I got it under my microscope

So thinking that the corrosion may have something to do with the fault, I cleaned off as much crap as I could with Isopropyl and found the soldered joints didn't look too clever so I cleaned those up using flux and solder braid as best I could without actually removing the chip.

It looks a lot better now (see pics) but on testing I found all this work made absolutely no difference, I still get the same error.

Maybe the Super IO is faulty or there is more crap underneath the chip. I don't know. Looking at the close up pics it looks like I maybe have a solder bridge, which I can check. It looked OK when I was tilting the board and looking manually with the microscope.

Can someone tell me how the Super IO actually switches the CPU to protected mode?

Does it toggle some logic level going to a CPU pin, or is it actually making the CPU process some opcode from the BIOS to load an internal control register or something like that? I'm sure I could find that out if I waded through the datasheets but hopefully someone can save me a bit of time.

And is it likely I am on the right track to fixing this fault?

Rich

[petehall347]

Re: Asus P5P43TD won't boot or beep with memory fitted

looks like it needs a good scrubbing to me and then the compressed air . and maybe soldering better

[ChaosLegionnaire]

Re: Asus P5P43TD won't boot or beep with memory fitted

i see a red brown cap with a Y vent on the mobo. is that a kzg or kzj cap? those caps are no good. probably bad caps causing the board not to post.

[dicky96]

Re: Asus P5P43TD won't boot or beep with memory fitted

Thanks I'll have a look for caps. I didn't notice any leaking/bulging ones.

Does anyone have a board view file for ASUS P5P43TD? I can find links to a couple of sites (plus one on ebay) but they all want me to pay. I don't mind paying for stuff I want/need, everyone has to make a living, but I doubt these sites actually own the intellectual property for what they are trying to sell - which to me just makes them 'opportunists' which is something I kinda object to.

[dicky96]

Re: Asus P5P43TD won't boot or beep with memory fitted

All the caps look fine and check out OK in circuit on my ESR meter. The brown ones are KZG, there are only 2 of those. All the others say FJS and are black/gold. I can change them anyway but don't have any 820uF 6.3V so I've ordered some off aliexpress.

Not mentioned before but I do have a known good CPU in this board and the socket pins all look fine.

I checked what looked like possible solder bridges on the Super IO but they are fine. There does look like more crap underneath the chip though, so I ordered some W83627DHG-A as well.

I don't think my 858D would be up to the job of changing the W83627DHG but I have a better hot air station on my 'to buy' list and may have that by the time the parts arrive.

I guess this motherboard is also put on one side now waiting for parts.

Anyway no rush as I have stated earlier I am only repairing these motherboards to improve my own skills/ability, not for any commercial value. Hopefully I'll pick up some more boards to look at when i go to the flea market this weekend.

Rich

[momaka]

Re: Asus P5P43TD won't boot or beep with memory fitted

Try inserting some pressure on the CPU socket before powering on the motherboad or try warping the motherboard under the CPU socket a bit (works best with the heatsink only sitting on top of the CPU and not bolted/tightened down.) It's rare, but I've seen BGA CPU sockets develop bad connections in the BGA.

Also, the corrosion on that SIO/LPC seems to go very high on the pins, as in, right into the chip. Generally when I see that on any chip, I consider it marginal - it may work, but it may not work for long, or at all.

That said, if the motherboard does NOT require you to always have a RAM stick in slot #1, try with one stick of RAM in any of the other slots and see what POST codes you get.

[dicky96]

Re: Asus P5P43TD won't boot or beep with memory fitted

Thanks Momaka, I'll try that.

The board does allow a single DIMM in any slot and I have tried that. Most of the time I get code F0 with the DIMM in slot A1 and code 40 with it in any other slot.

Occasionally I have seen code 40 with a singe DIMM in A1.

With two DIMMS I always get code 40.

Rich