2700X or 1900X for VMs, PCi'e gaming passtrough - Unable to decide

Hello fellow pc enthusiast – I’m in need on some input on my next pc.
My current pc is a 6600k, GTX 1080 + 16 GB ram, and it have served me very well. But for over a year now, I’ve wanted to switch to Linux. I used Linux mint on my old macbook for years, and Antergos on my T410S for the last year. I’m just so very tired of Windows 10’s shenanigans.
But I do game – hence the GTX 1080, and dual booting is not appealing to me.
But after all the virtualisation and PCI-e pass trough exposure from Wendell, I finally see sunlight after a long windows night.
And now for the new pc at hand.
I want to pass trough my GTX 1080 (which should be possible according to this guide: Ryzen Virtualization Success (GTX 1080ti passthrough with Windows 10 client)).
I also want to run different VMs for different purposes. At the same time. And maybe start learning some programming, some compiling etc. So I need something with high core count.
So I decided on the 2700X, Asus Crosshair VII + 32 GB 3200 MHz cl14 ram and a RX580. + the 1080 for pass trough. I have the Asus rog pg348q, and the 1080 fits it like vodka and myself.
At some point I also want to introduce 10 Gbe to my pc, for a highway to my freenas box.
The Crosshair VII have the necessary PCI-e slots for this – so it should all be gravy and vodka.

But as I’m about to order the parts I once again glance at Threadripper, and think – I’d like those extra PCIe lanes. It’s nice to have options down the line for maybe an extra Vega GPU for a different VM pass trough, or some other PCIe add in card.
The price difference here in Denmark between a 2700X + Crosshair VII, and a 1900X + Strix X399 is negligible. And If I really get into VMs I have the option for a higher speed higher core count TR4 CPU than AM4 can offer. And 2x16 GB vs 4x8 GB sticks is in the same ballpark price wise.


  1. Am I overthinking this, and should I start with the AM4 setup?
  2. Will the current X399 motherboards support the Zen+ based CPU’s – should I decide to pop in a higher core count Zen+ down the line?
  3. Will 4 core 8 threads at 4.2 GHz (AM4 Zen+) give better fps vs 4 core 8 treads @ 4Ghz (TR4 Zen) in the gaming VM? The resolution is 3440x1440 @ 100 Hz. My current 6600K is 4 core 4 threads @ 4.5 GHz.

The price difference is not a concern. My job pays well, rent is cheap and a good bottle of vodka is 30 $.

I look forward to some input – none of my friends get what it is I want to do with this at all :slight_smile:

if you’re gunning for 8 cores, id just go with the am4 socket, it’s kind of the “day to day” user chip’s
The main difference between the two chips really is the amount of pci-e lanes they have available, and unless you got a redunculus amount of nvme drives which all run in raid0, i doubt you’ll feel any difference, atleast when it comes to the 8 core TR.
You shouldn’t be thinking in as much of what do i gain right now, but rather what might i need in the future, if you choose TR, you’re locked to TR for future upgrades, if you go with AM4 you can drop in the next gen chip just as fine as you could the current gen, and at the same price’ish upgrade cost for the cpu.
Where TR you will pay a premium, also remember the current gen TR chips have had a year to drop in price, and are still first gen which means their price is lowered considerably.
but if you in the future want 16-20-24 cores, how ever many AMD will offer for the TR4 socket, go for the TR.

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i’m going 1900x

for a few reasons:

  1. more pcie lanes.
  2. more ram slots
  3. future upgrade potential for more cores

Ryzen will get you a machine that can do pcie pass through and virtual machines but the above points, especially in today’s DRAM market are relevant.

if you want more than 32GB of ram today, it’s fucking expensive. if you want to upgrade from say 16 GB today to 64 GB in future, on am4 you need to throw our memory sticks as you have only 4 slots.

the pcie lanes and future higher core counts are gravy. right now the kicker for me is memory pricing. i simply refuse to buy 64 GB today at today’s pricing, and i need more than 32 to do some of the stuff i plan to do with the box in future. a threadripper build gives me more flexibility to buy more memory later without throwing out the old stuff.

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Threadripper would be the best choice here, as you yourself said: PCIe lanes.
Hard to come by and for future expandability, especially when using VMs, needed.
If you want to passthrough things to VMs then you may even need additional USB cards or soundcards if using multiple VMs.
On AM4 you’re going to hit the limit fast concerning expandability. Btw. for most 10GB NICs you already need x4 or x8 lanes.
So let’s break it down a bit:
AM4: 24 PCIe lanes
x16 GPU (Can be splitted x8x8)
x4 NIC 10GB (Some cards) or x8 10GB NIC (Most cards)
x4 NVMe
x4 Chipset (Most boards have one x4 PCIe slot which is shared with the second NVMe slot, so you can only use one of them but not both at the same time)
Limit reached

TR4: 64 PCIe lanes
x16 GPU
x4 NIC 10GB (Some cards) or x8 10GB NIC (Most cards)
x12 NVMe (Most(All?) boards have three slots)
x16 GPU
x8 Other
x4 Chipset (Some boards have one x4 and/or two x1 PCIe slots from the chipset)
Limit reached

And the TR4 socket is there to stay for quite some time like the AM4 socket. X399 will very likely support Zen+ just not the “additional” features like XFR+ (or whatever it’s called). Btw. XFR is disabled as soon as you OC it, so it doesn’t matter either way.


1900X is a good choice… when Threadripper passthrough is more mature.

Threadripper has growing pains in terms of passthrough compatibility. It still currently suffers from PCi-E communication errors (correctable, but errors nonetheless) that the upstream kernel needs to fix.

Wait until it gets ironed out if you’re determined on threadripper. If you want a quick solution right now, the 2700x is hard to beat at the moment, but there is a rumored higher end chipset than X470 so when B450 drops, you might expect some info on that chipset.

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If you decide to go with am4 and the 2700X,
then it might be interesting to take a look at the Asrock X470 Taichi Ultimate board instead of the Asus crosshair VII Hero.
The reason for this being that the Asrock X470 Taichi Ultimate allready comes with a 10Gbe nic onboard.
I’m not sure yet about the compatibillity of that 10Gbe nic on Linux.
But atleast it comes with it onboard which is nice in your case maybe.
The Asus Crosshair VII Hero is definitelly a better board in terms of vrm design and bios.
However the Hero doesnt come with a 10Gbe onboard nic.
So it will cost you additional money and a pci-e slot to get 10Gbe.

The Asrock X470 Taichi Ultimate also is still a very decent board,
with a great vrm design aswell.

Of course if you decide to go with Thread ripper X399,
then you will have way more expending options since more pci-e lanes.
And also the abillity to upgrade to higher core count cpu´s,
and more memory.
But pci-e passtrough can be a bit shaky on certain boards with TR.
But i guess that those bugs will be ironed out at some point.

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10 GbE on xX70 chipset is a bit of a stretch imho. Well, definitely if you have multi-GPU.

typically you want to do high speed transfer to or from local storage and if you’re doing multi GPU you don’t have the bandwidth for it as the 10GbE NIC will(?) be driven via the chipset along with your SSD. unless i am mistaken on the way ryzen lanes are wired …

Thanks for the replies everyone, I really appreciate the input :slight_smile:

It really boils down to the PCIe lanes TR4 offers.

I wasn’t aware that Asrock had a X470 with onboard 10 Gbe, but I kinda only buy Asus. Not because of fan boyism, but simply because my local hardware dealer is an Asus partner. So if the hardware is faulty, I can simply return it and get a new one imminently. And they generally make good hardware :slight_smile:
(On a side note, when I assembled my current pc, the first two motherboards had different faults – Asus Z170 Hero – but since I could simply return them and get a new one at the same time, it wasn’t really an issue. Just a tad annoying.)

I know I would be annoyed with myself, if I run of of PCIe lanes or cores in six months, and hardware can be sold and new bought, but not without a write-off.
I’ll go with Threadripper, since it will give me the option of upgrading to higher core CPUs in the future, plus plenty of PCIe bandwidth for expansion and experimenting.

The maturity might not be there quite yet for pass through on X399, but then I’ll be part of the testing community that helps it through puberty :slight_smile: The machine will run Antergos, so the fresh kernel versions will come as quickly as they are released.

Time to whip out the wallet :money_with_wings:

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