Accessory PCIe risers are so confusing

[Min_Ahn]

I have a Dan Case A4 v2 with PCIe 2.0 riser (8KC3-0726-0300) which came with the case.
When v3 came out it advertised to have a 3.0 in it, so I automatically thought mine’s the outdated 2.0.
The most recent revision, the v4.1 claims to have PCIe 4.0 riser with part number 8KC3-0726-0250 according to the founder.
Is it a coincidence that the 2.0 and 4.0 have the exact same part number(except the last four digits which is the length)? Or does 3M not change their parts number for newer generations?
Or is my “2.0” riser capable for 4.0 use?

 

[riba2233]

your riser was never gen2, it is at least gen3 according to 3m website:

https://www.3mdeutschland.de/3M/de_DE/unternehmen-de/produkte/~/3M-8KC3-0726-0300-PCIe-Twin-Axial-Kabelgarnitur-300-mm/?N=5002385+3290403627&rt=rud

But it looks the same as the new one which should be gen4, so it could be that also.

 

[thelaughingman]

screw risers! I just moved back to classic layout because of this!

 

[SiKiaTriK]

What is beyond me is the fact that, despite not having the riser any chip or processing function itself, and being the same amount of pins from the very first generation you can call it gen"this" or "that" capable. Providing both motherboard and GPU are gen4 (as example) how a riser can limit the amount of data transfered? is it the purity of the materials used? the thickness of the lane / insulation itself? Always wondered

 

[riba2233]

What is beyond me is the fact that, despite not having the riser any chip or processing function itself, and being the same amount of pins from the very first generation you can call it gen"this" or "that" capable. Providing both motherboard and GPU are gen4 (as example) how a riser can limit the amount of data transfered? is it the purity of the materials used? the thickness of the lane / insulation itself? Always wondered

It is the shielding, eg. how much of outside EM interference can riser isolate from the pcie signal.

 

[kotproger]

High speed imposes special requirements and restrictions on data lines (not only interference). And the higher the speed (generation pci-e, for example), the stricter the restrictions. And if these requirements are not met to switch the connection to the maximum speed, then the connection will either with an error, or will work at a lower speed (generation).

 

[Min_Ahn]

your riser was never gen2, it is at least gen3 according to 3m website:

https://www.3mdeutschland.de/3M/de_DE/unternehmen-de/produkte/~/3M-8KC3-0726-0300-PCIe-Twin-Axial-Kabelgarnitur-300-mm/?N=5002385+3290403627&rt=rud

But it looks the same as the new one which should be gen4, so it could be that also.

Yup. I just contacted the founder of Dan Case and he confirmed that he reused the same riser cable he used for V1 and V2 3 years ago.
It is very misleading because V1 and V2 don’t say they supports PCIe 4.0, only the V4.1 says it does.

 

[REVOCCASES]

just for the science, here some pictures how common PCIe 3.0 riser cables look like inside:


this one uses 0.2mm diameter tin plated wires, each shielded by some kind of polymer coating and covered by rubber for protection

this one uses 0.2mm oxygen free solid copper wires and is fully wrapped by a metal-mesh-cloth for EMI shielding

the 3M one is definitely the most advanced: 0.25mm tin or silver plated wires, each one shielded/isolated and additionally shielding by an aluminum foil layer around the whole cable. Using better shielding and thicker wires may explain why this one works just fine with PCIe 4.0 and the others might have some issues with higher bandwidth.

(source)

Maybe interesting for this thread.

 

[Min_Ahn]

Maybe interesting for this thread.

It is indeed. It explains why this 3 year old cable is still compatible with the latest tech.

 

[Legion]

This might help people out there understand why there is so much incompatibility atm, And why still so many cases are sold with cheap S*** risers !!!!

 

[chilman408]

Yup. I just contacted the founder of Dan Case and he confirmed that he reused the same riser cable he used for V1 and V2 3 years ago.
It is very misleading because V1 and V2 don’t say they supports PCIe 4.0, only the V4.1 says it does.

Sorry about digging up an old topic.

But does 8KC3-0726-0300 support PCIe 4.0 or not?

I'm asking because this is the only item in stock at Mouser but 3m has a new P/N under 8KCE-0953-250 that is specifically spelled out for PCIe 4.0.

 

[confusis]

Sorry about digging up an old topic.

But does 8KC3-0726-0300 support PCIe 4.0 or not?

I'm asking because this is the only item in stock at Mouser but 3m has a new P/N under 8KCE-0953-250 that is specifically spelled out for PCIe 4.0.

Only one way to find out

On a brief glance, there has to be some reason 3M didn't just certify the older riser cable to gen 4 - seems they've made some tweaks on the newer model you quoted.

Likely, it's a signal integrity issue. Have you looked at alternative cables from other sources than Mouser?

 

[chilman408]

Mouser and Digikey are typical vendors we go with as other unknown vendors need to go through an approval process from a bean counter somewhere.