Question B760 vs Z790 ?

[Regev]

Hi, considering a board for the i9-14900 (non-K). Not going to overclock (probably undervolt, if anything), but I am eyeing the Z790 for the better VRMs. I like to get boards that are designed for overclocking, and then not overclock. Just for the extra stability and engineering.

One thing that caught my eye, someone wrote on Reddit:

"The more important consideration for most modern users, since overclocking is almost basically dead anyhow, would be that the B760 chipset boards have support for fewer PCIe lanes in total so users wishing to use a graphics card AND a bunch of storage devices might run into lane issues. Also of importance is the fact that the DMI interface of the B760 boards runs at only half the speed of Z790 boards. That might actually be of MORE importance than any other comparative features for some users."

My questions: (thanks in advance)

1. What exactly does he mean with the DMI interface running at half the speed on B760 boards?

2. If Z790 supports up to 20 Pcie4 lanes, while the B760 supports up to 10, what exactly happens when you plug a Pcie4x16 GPU to a B760? It only uses 10 lanes instead of 16? Doesnt make sense, cause I know lots of gamers opt for B760 boards. Would appreciate a clarification.

Total no. of PCIe Lanes	28	14
No. of PCIe 3.0 Lanes	Up to 8	Up to 4
No. of PCIe 4.0 Lanes	Up to 20	Up to 10

* There's a $130 difference between Gigabyte's B760 and Z790 ITX boards, in my area of availability.

 

[Lutfij]

There's a $130 difference between Gigabyte's B760 and Z790 ITX boards
You only have access to one PCIe x16 slot, you will get 16 lanes as stated in the product's description;
https://www.gigabyte.com/Motherboard/B760I-AORUS-PRO-DDR4-rev-1x/sp#sp
if that's the itx board you're looking at, and those lanes are allocated from the CPU. The chipset handles the other PCIe slots on a larger board, not to mention other M.2 sots.

 

[35below0]

Total lanes and how lanes are used/restricted can have consequences when it comes to GPUs and M.2 drives. Something like the problem this user is having: https://forums.tomshardware.com/thr...and-m2-drive-gen5-question-on-config.3838064/
Note that the board in question is a z790 board.

I'm with you when it comes to using the more expensive chipset motherboards even if i'm not interested in overclocking. The B760 chipset is not all that cut down compared to the Z790 though. But that is the Intel chipset itself.
However what the motherboard manufacturers choose to do with the board layout, including stuff like VRMs and lanes, can make a far bigger difference than just the choice of chipset.
The chipset imposes limits of it's own, but a motherboard can implement less than the chipset can support.

Reading the fine print is a must. More expensive motherboards can still come with all kinds of gotchas. Likewise, some cheaper boards have almost no penalties of consequence at all.

 

[geofelt]

Here is a chart of the chipset differences for lga1700:
https://en.wikipedia.org/wiki/LGA_1700

Most will not find any differences that matter.

 

[Regev]

Oh, gotcha. So the CPU itself will support the 16 lanes for the GPU, and the other 14 (in case of B760) or 28 (Z790) comes from the chipset itself, is it right?

Would you shell the extra $130 for the Z790 simply for the better VRMs ("105A Smart Power Stage - 10+1+2 - 2X Copper PCB" vs "90A Smart Power Stage - 8+1+1 - 10-Layer & 2X Copper PCB") and the PCIe5 GPU support?

 

[geofelt]

If budget is not an issue, by all means spend an extra $130 and go Z790.
But, I suspect you would do much better by adding $130 to your cpu budget in the first place.

 

[Regev]

If budget is not an issue, by all means spend an extra $130 and go Z790.
But, I suspect you would do much better by adding $130 to your cpu budget in the first place.

I took the 14900

 

[Regev]

I got 2 DIMM slots. At what latency and speeds are diminishing returns not worth it (for productivity uses, not gaming) ? Found a 2x32 pair of 6400, CL34 for $230

 

[geofelt]

Worth is something only YOU can determine.
Intel, in general, unlike ryzen does not depend on fast ram for performance.
There are exceptions for some apps, but I can't tell you which they are.
Usually, more ram trumps faster ram.
With some motherboards, you can run 2 x 48gb sticks.

 

[Regev]

Guys, can the ITX boards really hold up an i9 (stock) ?

The best VRMs I could find on an ITX Z790 is a 10+1+2 with 105A Smart Power Stage. It costs almost $300. In contrast, a B760 MicroATX (Asrock Riptide) is 40% of the price, and offers 14+1+1.

 

[geofelt]

ITX motherboards are, by definition small with limited space for components.
They are not designed for overclocking that might require extra component vrm and cooling.
That said, if one needs a I9 with many threads, you can use a I9.

As an example, I had an extra I9-12900K and put it into a Asus rog strix B760-I motherboard with a stock RH1 cooler and it is doing fine.
CPU-Z stress test shows a couple of P cores going into throttling and recovering.

 

[logainofhades]

I would take the B760 and use the $130 savings on storage, or a better gpu.

 

[thestryker]

Regarding VRM on ITX they're all pretty much the same in being limited. So long as you keep power limits enforced it should be fine. If you are able to move to MATX you will be able to find some more robust VRM designs.

1. What exactly does he mean with the DMI interface running at half the speed on B760 boards?

The chipset is connected to the CPU via PCIe interface and on Z series this is PCIe 4.0 x8 and on B series it is PCIe 4.0 x4. The specific maximum IO differences can be found here (though every board uses different implementations): https://ark.intel.com/content/www/us/en/ark/compare.html?productIds=229720,229719

 

[Regev]

The chipset is connected to the CPU via PCIe interface and on Z series this is PCIe 4.0 x8 and on B series it is PCIe 4.0 x4. The specific maximum IO differences can be found here (though every board uses different implementations): https://ark.intel.com/content/www/us/en/ark/compare.html?productIds=229720,229719

What does that mean - in the real world? Faster performance in any type of work?

 

[thestryker]

What does that mean - in the real world? Faster performance in any type of work?

No it's purely IO, so you'll get more PCIe lanes, USB ports etc. The only real world impact I could see is if you were using multiple SSDs/high speed networking off the chipset lanes which would work worse off of B series.

 

[35below0]

Also, Intel H770 motherboards practically don't exist. (they do but they are very rare)