How to test GPU / CPU accessed the BIOS without an Oscilloscope LER
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- Опубликовано: 11 сен 2024
- LER #183 If you have a graphics card or motherboard that powers on but does not boot, it is useful to test if the GPU/CPU is accessing the BIOS to execute code. Normally you would do this using an oscilloscope... but what if you don't have one?
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Thank you
Richard
Old trick and you made me recall great memories bro;
BUT I WOULD LIKE TO POINT OUT SOMETHING HERE TO WHOM WANTING TO TRY IT:
PLEASE DON'T USE EARPHONES OR YOU MAY DAMAGE YOUR EAR.
Many thanks for this video bro
I have an oscilloscope but I still enjoyed watching this and found it interesting.
I’ve seen a similar idea on a video from Grants Pass TV Repair channel where he made an amplified microphone to hear electrical activity (high frequency whine, frequency changes etc) as a troubleshooting technique.
It’s also useful to hear the hard drives to see what pattern of noise they exhibit in case you suspect failure.
For sure I didn't invent this technique - I learned it in the 70s, together with signal injection, as way to test and diagnose audio circuits - I just thought it could also be applied to detect very short duration digital pulses as well - and it works very well it seems😀
@@LearnElectronicsRepair That technique is great yeah, used it for years.
it's the first time i see someone mentioning it in YT; but in fact tbh i am not that fan of youtube i just encountered this video in Adamant IT server
Excellent idea to find if the BIOS is accessed. Especially this will eliminate the PCH and CPU from the equation. PCH is required to translate the access to ffff_fff0 (intel real mode) to SPI commands for the BIOS. Thanks for spending all the time explaining patiently to us. The best channel for electronics troubleshooting and repair.
Good video. I never thought about a GPU accessing the bios. Thanx for showing that schematic.
A GPU, or any other sort of add on card, needs to inforrm the PC of it's specifications and parameters when the PC boots, during the POST.
There is a detect pin in the PCIe or PCI slot that is connected to ground when you insert a card. This simply tells the PC that there is a card inserted. The PC then sends an identification request to the card. As the GPU has no internal data storage, and the video RAM is volatile, this info is held in the BIOS chip on the graphics card.
The GPU is supposed to read this info from the BIOS and reply to the PC. Testing if this occurred is an important part of the diagnosis when you have a graphics card with all the voltage rails present but it does not detect.
Brilliant idea! Simple, effective and cheap. Bravo! Regards from Italy.
Cheap is always the best - when it works 😉
When I was a kid, in late 80 and beginning of 90, I remember seeing games being installed into some type of console's using cassette player, remember it use to make similar sounds while installing and it use to take forever.
This reminded me of those days.
Oh yeah, that is what I thought - it sounds just like a Sinclair Spectrum 48 loading!
Or a Commodore Vic-20 or Commodore 64. Ah the good old times! 😔
Great tip mate, this will help me lots, thanks again and keep up your fantastic work, we all love in this channel
You're welcome
in an ever changing modern world that is pushed to be reliant on the most expensive equipment to diagnose things tis nice to see some of the old school techniques are still very applicable,
Very much so. You arn't the Andy Davies from Stoke-on-Trent are you - that worked in the same workshop as me in the early 90s?
You are my HERO
I prefer the speaker solution over the scope. I'm fixing motherboards and graphics cards, but basically never use oscilloscope, PCI-E/TPM debug card, thermal camera and multimeter are enough for 99% of the job.
Usually if I don't find the problem within 15 min, I have to chase down the problem on the PCB and it will be 1-2 hour poking and probing around.
Last time I used the speaker method for a faulty Audio channel, because the measuring poking method doesn't worked first, I couldn't find difference between the two channels. At the and I found the faulty FET, it wasn't burned out to short as usual, but it had about 1K resistance between D-S.
What problem do you hate the most to solve/fix? Mine is ASUS/GIGABYTE VRM with FET drivers.
I hate the sort of fault where everything seems to be OK (voltage supplies etc) but it just doesn't work! Which thermal camera are you using?
Brill as always. Thanks.
wowwww a great idea!!! thnks so much rick!
Great video, love the resourcefulness. Is there a difference between this and just looking for voltage to see if the chip has been accessed?
Great information. A friend has a PC which powers one, CPU fan spin, but no display via onboard or GPU. So I'm thinking it might be a bios fault. I might try reading pin one with my new oscilloscope.
really good idea Richard thanks
Glad you liked it
@@LearnElectronicsRepair I have an old logic probe on a shelf been there since 1990's wonder if that will work ? Never used it.
great idea, thank you :D
Very Cool..
Great video.However if one has an oscilloscope,how many MHz it has to be to detect and display the pulse from bios chips?
Even a very cheap basic oscilloscope can do that. I proved it on this video
ruclips.net/video/Lv_MvDMxHc4/видео.html
Heya, oh wouw yes of cores that shematic will work. but does it tell you also if the c-mos is working ?
Superb 👌🏻
Interesting Idea, thanks for sharing :)
You are welcome
Bravo!
GRACIAS COMPADRE
Smart one ;-)
Smart !
wow, nice
is there a possible way to do this with a pc power led or hdd led thanks very interesting video much appreciated.
Is there a way of testing a cpu. Off the board???
Can you fix my wife for me?.
Well I have a pulse counter on the way..... 😅
@@LearnElectronicsRepair ha ha.
Might be better taking it back for a refund?!
🤔🙄
It’s usually the wife trying to fix the husband. Learn from their failure and enjoy the remaining functionality or replace it if the feature(s) you require don’t operate as desired.
For my own interest I looked at the enable pin of my Acer schematic bios chip and this comes from the 3v PCU power supply not the PCH chip!
The BIOS is normally connected to what was called the southbridge, on the 'slow' bus, not the PCH. I don't recall saying it was connected directly to the PCH ?
So if the GPU doesn`t access BIOS ? What to do then ? I have an RX5700 XFX - I also posted it on the badcaps forum . Thanks
Try the board in PCIe x1 mode using a mining adapter
Check the resistance (in diode mode) from all the PCIe x16 lanes to ground - on both sides, the tracks that go directly and the ones that go via little capacitors, On the ones that go via capacitors check from each capacitor itself, not the PCIe finger. They should all read the same, any reading widely different suggests a faulty GPU chip
Check the reset signal coming from the PCIe connector (SMRST) - this normally goes via couple of transistors or a logic gate and is probably ANDed with the Power Good from the last VRM to power up (Vcore in your case). Check if that circuit works.
Check the 25MHz crystal is oscillating
@@LearnElectronicsRepair Just measured a few pairs of PCIe and they don`t give back same numbers . Sadly the GPU chip is gone as you stated
@@Goblin-9.9.9 So yes that is the problem. Sorry to hear it but consider the bonus that you learned new skills to help you in future 🙂
@@LearnElectronicsRepair Surely I learned a whole bunch of new things from you . Thanks a lot for the hints . Cheers
@@Goblin-9.9.9 I just answered on badcaps - from your message there I think you are measuring the wrong places
Please check my reply, and check this PCIe pinout
linustechtips.com/topic/547139-rip-motherboard-buyer-beware-cheap-pcie-riser-cables/
After the short section of PCIe and the key slot, You can see the 16 lanes (pairs of wires) with the capacitors on one side and without capacitors on the other side. All the ones with capacitors should read same as each other and all the ones without capacitors should read same as each other - but different form the ones with capacitors. 32 pairs in total. I hope that makes sense
You fixed the board by poking it with a stick. Common tachnique.
Oh, I'm better than that these days - now I usually don't need the stick and just give it a stern look!!!