Why can't we have iGPU AND PCIe lanes?
Why can't we have iGPU AND PCIe lanes?
I'm currently running a Xeon E3-1231v3. It's getting long in the tooth, supports only 32GB RAM, and has only 16 PCIe lanes. I've been butting up against the platform limitations for a couple of years now, and I'm ready to upgrade. I've been running this system for ~10yrs now.
I'm hoping to future proof the next system to also last 8-10 years (where reasonable, considering advancements in tech and improvements in efficiency), but I'm hitting a wall finding CPU candidates.
In a perfect world, I'd like an Intel with iGPU for QuickSync (HWaccel for Frigate/Immich/Jellyfin), AND I would like the 40+ PCIe lanes that the Intel Xeon Scalable CPUs offer.
With only my minimum required PCIe devices I've surpassed the 20 lanes available on desktop CPU's with an iGPU:
- Dual m.2 for Proxmox ZFS mirror (guest storage) - in addition to boot drive (8 lanes)
- LSI HBA (8 lanes)
- Dual SFP+ NIC (8 lanes)
Future proofing:
High priority
- Dedicated GPU (16 lanes)
Low priority
- Additional dual m.2 expansion (8 lanes)
- USB expansions for simplified device passthrough (Coral TPU, Zigbee/Zwave for Home Aassistant, etc) (4 lanes per card) - this assumes the motherboard comes with at least 4-ports
- Coral TPU PCIe (4 lanes?)
Is there anything that fulfills both requirements? Am I being unreasonable or overthinking it? Is there a solution that adds GPU hardware acceleration to the Xeon Silver line without significantly increasing power draw?
Thanks!
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iGPU is just integrated GPU on the CPU die. That is going to use pcie lanes for communication.
Wiring up a iGPU, as a cpu architect, you have two options:
- direct interconnects (low latency, no space, no extra heat)
- MUXed interconnects (latency, complexity, space, and heat on die), but even then you would have to choose between using the iGPU and having external PCIe lanes anyway
I think most designers have gone with direct interconnects
Sounds like your real requirement is just more pcie lanes, I believe epyc chips will provide in abundance
https://www.amd.com/en/products/processors/chipsets/am5.html
You can look at pci-e lanes available by model here.
Also you can use newegg to search moterboards by usable pci-e lanes.
Thanks. I'll be the first to admit a lack of knowledge with respect to CPU architecture - very interesting. I think you've answered my question - I can't have QuickSync AND lanes.
Given I can't have both, I suppose the question pivots to a comparison of performance-per-watt and number of simultaneous streams of an iGPU with QuickSync vs. a discrete GPU (likely either nVidia or Intel ARC), considering a dGPU will increase power usage by 200W+ under load (27c/kWh here). Strong chance I am mistaken though, and have misunderstood QuickSync's impressive capabilities. I will keep reading.
I think the additional lanes are of greater value for future proofing. I can just lean on CPU without HWaccel. Thanks again!
If power consumption is an issue then I'd recommend the arc a310 which can only draw up to 30 watts. I've been using one for a while and it can easily handle several 4k streams without issue.
Thanks. This is a pretty compelling option. I hadn’t looked at the entry level arc, but when it comes to encode/decode it seems all the tiers are similar. 30W is okay, and it’s not a hard limit or anything, just nice to keep bills down!