On Thu, 5/14/2026 1:53 PM, pinnerite wrote:
Desperate to replace the 13 year old system used as an HTPC,
based on a Gigabyte Mini-ITX motherboard, I searched for a replacement.
It had to have a PCIe slot to take a Turbosoft DVB-T2 TV card.
It also had to take an AMD Ryzen 7700 7 because I had two brand new and
boxed that I couldn't sell. (Long story).
I found an ASRock B850M Pro-A microATX that seemed perfect. Except!
a microATX is larger than a Min-ITX board.
That turned out not bto matter.
It all went together OK, except the system would not recognise either
of my two Turbosoft TV cards. No manual is supplied with boards these
days so you have to download and print it yourself. Except!
There are no BIOS details in it. I spent many hours trying to tweak BIOS options but the system (Mint 22.3) could not seem to find a fix. In the
end I recruited my pal Hazim, a professional system builder and
debugger. As both TV cards had worked in my other machines, I wondered
if the problem was the motherboard itself.
Hazim, replaced the TV card with a network card. Sure enough, as we
booted up, the device's lamps twinkled. So the motherboard itself was
not faulty.
I had written to Turnosoft technical support. Their suggestion to
change the PCIe socket's link speed frpm Gen1 (my choice), to Gen2 di
not work.
Hazim did not trust Linux so we plugged in his portable Windows 10
portable SSD system and booted on that. It made no difference of course.
Although I did admire Windows driver handling windows. I had forgotten
that it did have some virtues.
Hazim's advice? Don't buy ASRock products. They are the cheapest and it shows. My experience with motherboards during the last 12 months is
also to avoid ASUS because their boards have no diagnostic lamps. I try
to use Gigabyte because they do, although their user manual is also
spartan on configuring the BIOS but it does have some info.
I hope this helps someone else.
Regards, Alan
As an engineer, I don't believe in superstitions.
Just cold hard facts.
Was Secure Boot turned off ?
For video cards, they can be VESA BIOS, they can
be GOP BIOS, they can be GOP BIOS with some
sort of certificate for boot purposes. And even when
you turn off Secure Boot, the Secure Boot system is
not entirely passivated, and a screwed up certificate
store can still influence the way the BIOS behaves
during early POST.
And of course Hazim flashed up the motherboard to the latest BIOS.
While that does not help quite as much on an Asrock product,
it is still the recommended procedure on new computer equipment.
Twenty years ago, our advice was the exact opposite, because
of the risk of brickage, you would not flash the thing. But
today, we are all for flashing of the UEFI BIOS, as that is part of
patching out issues with the Secure Boot (Black Lotus).
A TV Tuner, is not a "key part" of booting anything. It
only comes into play, when the OS comes up. But a historical
observation is, that the BIOS will not only ignore card
types it does not recognize, it will also disable the chip select
such that you cannot try when the system comes up. The gating
the BIOS does, can be quite effective (for the "Plug and Play OS" "Yes" setting).
Now, your system won't have this, but there are an unending
series of possibilities in computers.
https://support.hpe.com/hpesc/public/docDisplay?docId=sd00001068en_us&page=GUID-D347CDE5-AA66-4CF6-BBDE-FDECBDBA3B99.html&docLocale=en_US
"Obtaining UEFI serial output log data"
Since UEFI is its own little OS, you never know what might be
lurking in there, in the way of assistance.
*******
Did you ask your AI, specific and pointed questions about
older cards of a certain "type", regarding compatibility issues ?
The compatibility matrix is quite a mess now, with more
possibilities than I can even generate a table for you.
Just video cards and their GPU, there are well more than
two types involved now. There could be four types or
four possibilities, that affect "compatibility" on new kit.
Legacy VESA
UEFI GOP VBIOS
Both (Hybrid, was supposed to be common)
UEFI GOP with trusted computing certificate <=== don't have details, cannot be positive
If this motherboard is a UEFI only, does it have
"Secure Boot" "No" capability ? Even if we can no longer
have UEFI/CSM systems for maximum flexibility, we at least
need UEFI-SecureBootOff as an option, for our sanity.
There is already some sort of issue where a GPU is not
"trusted" and causes a problem if SecureBoot is ON.
I've already had a PCIe video card rejected, with the
"missing video" error code, and that might be the VBIOS
is the wrong type.
I did not clean this up, but you just need to read the exception
at the bottom, as a possibility. For the most part, the LLM-AI
relies on the pci-sig statements on backward compatibility.
*********************** A Section Of a CoPilot Answer ************************* **Short answer:**
All PCI Express versions from **1.0/1.1 through 5.0** are *intended*
to be electrically and logically backward? and forward?compatible.
### Electrical / Protocol Compatibility Matrix
| Card ? / Slot ? | PCIe 1.0/1.1 | PCIe 2.0 | PCIe 3.0 | PCIe 4.0 | PCIe 5.0 |
|-----------------------|--------------|----------|----------|----------|----------|
| **PCIe 1.0/1.1 card** | ? | ? | ? | ? | ? |
| **PCIe 2.0 card** | ? | ? | ? | ? | ? |
| **PCIe 3.0 card** | ? | ? | ? | ? | ? |
| **PCIe 4.0 card** | ? | ? | ? | ? | ? |
| **PCIe 5.0 card** | ? | ? | ? | ? | ? |
**There are no officially incompatible combinations.**
All versions use the same link?training mechanism (LTSSM), lane negotiation, and fall?back speeds.
## Why compatibility works
PCIe maintains compatibility through:
1. **Link training (LTSSM)**
Every PCIe device and root complex begins at the lowest common denominator and negotiates upward. If a device cannot train at a higher speed, the link falls back automatically.
2. **Same encoding families (with version?specific improvements)**
- PCIe 1.x / 2.x: **8b/10b**
- PCIe 3.0+: **128b/130b**
Even though encoding changes, the negotiation happens *before* high?speed signaling begins.
3. **Same electrical interface**
Signaling amplitude, lane polarity inversion, equalization, and channel requirements evolve, but backward compatibility is preserved by design.
4. **Same software model**
Configuration space, BARs, capabilities, and enumeration remain consistent.
## Known Real?World Exceptions (Vendor Bugs)
These are **not** spec-level incompatibilities - they are implementation defects:
### 1. **Early PCIe 2.0 GPUs failing in PCIe 1.0/1.1 motherboards**
- Some Radeon HD 38xx / 48xx and early NVIDIA 2xx cards failed to train at Gen2 or even Gen1 speeds on older chipsets.
- Vendors issued **VBIOS updates** to force **Gen1 mode** (2.5 GT/s) because the
motherboard?s signal integrity could not meet Gen2 requirements.
*********************** End: A Section Of a CoPilot Answer *************************
Oh, I forgot one other aspect.
When a motherboard has an "excess" of NVMe slots, that excess
comes with "we will disable slot 3 if you put an NVMe
into the bottom connector on the board". There are population
rules, which disable certain slots, as a function of where
you stick NVMe and/or video cards. Let us check your manual now, for this.
Page 4
https://download.asrock.com/Manual/B850M%20Pro-A.pdf
"If M2_3 is occupied, PCIE2 will be disabled"
On a new system, I would be tempted to do test-bringup
while using a SATA drive. Even if you are not booting
from the M2_3 NVMe slot, you MUST remove the NVMe physically,
so it stops flipping the mux the wrong way. The CPU/Chipset
makers are doing us no favours, with all this lane-sharing
crap that disables things. You really have to read the
manual carefully, to "find that one sentence".
Paul
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