PCIe bifurcated 4x4 u.2 cards?

[toomuchstuff]

So I've got an EPYC system with plenty of slots and lanes... I set up one of those ASUS nvme x16 cards and that's cool, but I figure why not u.2 enterprise instead.

Does anyone have any suggestions for x16 bifurcated (x4x4x4x4) cards? Would love if it would support PCIe 4, but I can live with 3 today. u.2 support is all I'm looking at, but maybe u.3 if someone says it's working for them.
I see one on Newegg for around $70, but it doesn't really say PCIe 3 or 4 in the spec. I'm sure if it is straight passthrough it'll work fine with either, but I also don't know the pinout difference for u.3 and if that's even something to consider from what I've seen of other people's trouble threads getting u.3 going.

Thanks!

 

[i386]

I'm using a AOC-SLG4-4E4T in my 745 chassis. Not the cheapest, but it came with full and and low profile and it's from a known brand

 

[Tech Junky]

@toomuchstuff

U.2 works with u.2
U.3 works with both 2&3

Beware of the drives though as some run hot and need direct cooling whereas some run cooler like Kioxia.

 

[Sean Ho]

Another option is a $20 passive 4x8643 card, no retimer so you need to watch the signal loss. Whether to use 8643 vs 8654 SlimSAS vs 8642 OCuLink also depends on cabling, which might not be cheap. And whether you're using a backplane.

 

[toomuchstuff]

Thanks for the replies

I'm using a AOC-SLG4-4E4T in my 745 chassis. Not the cheapest, but it came with full and and low profile and it's from a known brand

That's interesting, do these work without a SuperMicro board? I'm running several ASRock ROMED8-2T boards. With the retimer on board maybe I can get away with cables on pcie 4, idk, if so that could work with an icy dock setup when I change cases.

@toomuchstuff

U.2 works with u.2
U.3 works with both 2&3

Beware of the drives though as some run hot and need direct cooling whereas some run cooler like Kioxia.

Thanks for the clarification on u.2/3. I'll keep cooling in mind, depending on the drives I guess I might have to put my other cards in between for airflow. This is what I found on a quick search: Linkreal 4x4. I see it has an open back, but I would imagine the drive case is going to make a big difference if it has fins for heat dissipation.

Another option is a $20 passive 4x8643 card, no retimer so you need to watch the signal loss. Whether to use 8643 vs 8654 SlimSAS vs 8642 OCuLink also depends on cabling, which might not be cheap. And whether you're using a backplane.

Yeah, I'm not quite sure how long of cables can be ran without a retimer with pcie 4. My case doesn't have a NVME backplane but I've got 4 pcie slots available for cards and don't care about external hotplug anymore so that's why I'm thinking of pcie adapters.

 

[Tech Junky]

fins

I used logic and got drives with fins thinking they would run cooler but they didn't survive longer than a week. Some others reported them hitting 70 just sitting idle and my non finned Kioxia is usually around 40.

If you need the slim versions they're usually under 8TB and larger capacity drives are 15mm which could be an issue if you're packing them like sardines. The other issue with the PCB approach is if your mibo splits the lanes when adding a other card may result in not all drives working.

 

[nabsltd]

I'll keep cooling in mind, depending on the drives I guess I might have to put my other cards in between for airflow. This is what I found on a quick search: Linkreal 4x4. I see it has an open back, but I would imagine the drive case is going to make a big difference if it has fins for heat dissipation.

As @Tech Junky said, it's really about the drive itself for heat. I have an Intel 6.4TB that idles at under 30°C and hits about 55°C at load, while an HGST 3.2TB sits at about 45°C at idle, and gets close to 70°C at load.

For that card, you'd need good front-to-back cooling. I have no issue with that style card in a 4U server chassis with a fan wall in the middle (about 2-3" from the end of the card), but I suspect you'd have an issue if the fans were at the front.