Discussion Minisforum BD790i (Ryzen 7945HX mobile chip in a Mini ITX motherboard) vs an actual 7950X?

[JQM]

This is the Minisforum board: https://store.minisforum.com/collections/all-product/products/minisforum-bd770i?sscid=81k8_jiewt&
So obviously it's soldered on and can't be replaced, since it's a mobile CPU. From what I can gather the 7945HX is, quite literally, the desktop's 7950X at a lower wattage? I believe Intel does a similar thing with the absolute highest-tier Raptor Lake chips on mobile too, being the same chip as the desktop ones (which, for Intel, is why the higher end laptops are so prone to the Raptor Lake failures)? The Minisforum implementation of it is a bit special with a 100W limit instead of 75W like the laptop one normally is.

Is it actually the same chip? If so, is it expected to run the same as the 7950X at a given wattage point (i.e.: both are at 80W, or something)? And I figure the rest of the system is more efficient on energy as well given that it uses SO-DIMMs? Although I think SO-DIMMs are a bit slower, right?

 

[rfarmer]

You can ask @MarcParis, he has a build log here using the BD790i with the 7945HX.

 

[MarcParis]

This is the Minisforum board: https://store.minisforum.com/collections/all-product/products/minisforum-bd770i?sscid=81k8_jiewt&
So obviously it's soldered on and can't be replaced, since it's a mobile CPU. From what I can gather the 7945HX is, quite literally, the desktop's 7950X at a lower wattage? I believe Intel does a similar thing with the absolute highest-tier Raptor Lake chips on mobile too, being the same chip as the desktop ones (which, for Intel, is why the higher end laptops are so prone to the Raptor Lake failures)? The Minisforum implementation of it is a bit special with a 100W limit instead of 75W like the laptop one normally is.

Is it actually the same chip? If so, is it expected to run the same as the 7950X at a given wattage point (i.e.: both are at 80W, or something)? And I figure the rest of the system is more efficient on energy as well given that it uses SO-DIMMs? Although I think SO-DIMMs are a bit slower, right?

Between 7945HX and 7950X there is no difference on the compute side (CCDs), but there are slight on the i/o die.
7945HX has a bit more powerful igpu, normally connected only to 8x to main pcie slot, but minisforum managed to keep x16 lines (compatible with bifurcation) on the BD770i/BD790i. You have also 2xm.2 x4 gen 5...but minisforum is not sharing exact details on pcie lanes mapping. My personal testings found GPU & 2 m.2 are 16/x4/x4, for sure gen 4...but I didn't have anyway to test gen5.
Biggest gap is on the RAM, limited to 5200MTS speed on the 7945HX.

Overall, BD790i is a pretty beefy tiny beast..

 

[JQM]

Between 7945HX and 7950X there is no difference on the compute side (CCDs), but there are slight on the i/o die.
7945HX has a bit more powerful igpu, normally connected only to 8x to main pcie slot, but minisforum managed to keep x16 lines (compatible with bifurcation) on the BD770i/BD790i. You have also 2xm.2 x4 gen 5...but minisforum is not sharing exact details on pcie lanes mapping. My personal testings found GPU & 2 m.2 are 16/x4/x4, for sure gen 4...but I didn't have anyway to test gen5.
Biggest gap is on the RAM, limited to 5200MTS speed on the 7945HX.

Overall, BD790i is a pretty beefy tiny beast..

Interesting. Would the 7945HX be easier to cool than the 7950X? Or would there be no real difference there either?
I mean, I know the 7950X has a higher wattage limit theoretically here, but if we're talking small profile like this I don't think it's reasonably being used up to 100W anyway?

The RAM speed is a bit of a downer right? Zen 4 really likes 6000MHz+?

 

[MarcParis]

Interesting. Would the 7945HX be easier to cool than the 7950X? Or would there be no real difference there either?
I mean, I know the 7950X has a higher wattage limit theoretically here, but if we're talking small profile like this I don't think it's reasonably being used up to 100W anyway?

The RAM speed is a bit of a downer right? Zen 4 really likes 6000MHz+?

For thermals, difficult to say or test... At the same TDP, they should perform equally.

For RAM, definitely 6000MTS remains the sweet spot (same as the infinite fabric, linking CCDs)

 

[heyitsjel]

I was actually thinking of using one of these for a NAS... any chance you know if you can use an M.2 adapter in one of the dedicated M.2 slots, for say, a 10g NIC?

ie. use the pcie 16x slot in x4x4x4x4 mode with an M.2 riser/adapter board (eg. Asus Hyper M.2) for 4x nvme's, then use an M.2 adapter in one of the dedicated gen5 M.2 slots for something like a Mellanox ConnectX 10g NIC.

Currently have a similar setup using an 11th Gen (rocket lake) ITX build... basically use the x16 gen 4 slot bifurcated to x8x4x4 with 3x nvme's (gen4), and then the 4th nvme is in a dedicated gen4 m.2 slot, and an m.2 adapter in the final gen3 M.2 for the ConnectX-3.... the only downside is power consumption is quite high, even when idling... and I'd really like a spare m.2 slot for an additional nvme (apps/critical backup).

 

[MarcParis]

I was actually thinking of using one of these for a NAS... any chance you know if you can use an M.2 adapter in one of the dedicated M.2 slots, for say, a 10g NIC?

ie. use the pcie 16x slot in x4x4x4x4 mode with an M.2 riser/adapter board (eg. Asus Hyper M.2) for 4x nvme's, then use an M.2 adapter in one of the dedicated gen5 M.2 slots for something like a Mellanox ConnectX 10g NIC.

Currently have a similar setup using an 11th Gen (rocket lake) ITX build... basically use the x16 gen 4 slot bifurcated to x8x4x4 with 3x nvme's (gen4), and then the 4th nvme is in a dedicated gen4 m.2 slot, and an m.2 adapter in the final gen3 M.2 for the ConnectX-3.... the only downside is power consumption is quite high, even when idling... and I'd really like a spare m.2 slot for an additional nvme (apps/critical backup).

well, bifurcation seems operational on the 16x pcie slot. I see no reason why m.2 to 10gbe RJ45 won't work on one of the m.2 slot.

 

[heyitsjel]

well, bifurcation seems operational on the 16x pcie slot. I see no reason why m.2 to 10gbe RJ45 won't work on one of the m.2 slot.

Excellent to know!

From what I can see, the bios is pretty limited, but does offer you to select the pcie gen/speed? (ie. Automatic; gen3/4/5). Any chance if you know whether M.2 pcie gen can be selected manually?

I guess my only concern now, is that the drives are Gen4, while the NIC is Gen3....

 

[MarcParis]

Excellent to know!

From what I can see, the bios is pretty limited, but does offer you to select the pcie gen/speed? (ie. Automatic; gen3/4/5). Any chance if you know whether M.2 pcie gen can be selected manually?

I guess my only concern now, is that the drives are Gen4, while the NIC is Gen3....

you can select pcie speed (auto, gen3/4/5) on the bios. However I don't remember any option to split between PCIe & m2.