I've been using the same macbook air since 2011, and as a graduation present to myself I was going to build a nice PC to experiment with some open source LLMs and also use as a gaming machine to play some games (probably Baldurs Gate 3). I have not built a computer before so I would appreciate any feedback.
The main difficulty is that I would like to get dual RTX 4090s to run some of the larger LLMs (LLAMA 2 70b requires about 35gb of vram). In order to fit, I was going to go with dual MSI GeForce RTX 4090 SUPRIM LIQUID Xs since they each only take up 2 PCIE widths instead of the usual 3.
A couple of notes/questions
Does this look like a reasonable build? I would greatly appreciate any thoughts or concerns y'all might have.
CPU: (1) Intel Core i9-13900K Raptor Lake 3.0GHz Twenty Four-Core LGA 1700 Boxed Processor - Heatsink Not Included ($555.98 EACH)
Motherboard: (1) MSI Z790 MPG Carbon WiFi Intel LGA 1700 ATX Motherboard ($399.99 EACH)
RAM: (1) G.Skill Trident Z5 RGB 96GB (2 x 48GB) DDR5-6400 PC5-51200 CL32 Dual Channel Desktop Memory Kit F5-6400J3239F48GX2-TZ5RK - Black ($399.99 EACH)
Case: (1) Lian Li Lancool II MESH Type C RGB Tempered Glass ATX Mid-Tower Computer Case - Black ($109.99 EACH)
Power Supply: (1) EVGA SuperNOVA 1600 P Plus 1600 Watt 80 Plus Platinum ATX Fully Modular Power Supply ($344.99 EACH)
Video Card: (2) MSI GeForce RTX 4090 SUPRIM LIQUID X 24G Hybrid Cooling 24GB GDDR6X PCIe 4.0 Graphics Card ($1,799.99 EACH)
M.2 / NVMe SSD: (2) Inland Platinum 2TB SSD NVMe PCIe Gen 3.0x4 M.2 2280 3D NAND Internal Solid State Drive, PCIe Express 3.1 and NVMe 1.3 Compatible, The Ultimate Gaming Solution ($215.99 EACH)
Heatsink: (1) Noctua NH-D15S Chromax Black CPU Cooler ($119.99 EACH)
Thermal Compound: (1) Noctua NT-H1 High-Performance TIM - 3.5g ($10.99 EACH)
thanks in advance!
Few things to touch upon here. The dual RTX 4090's for the larger LLMs should work fine. Gaming wise, you'll mostly only be using a single GPU unless you use an API that supports explicit multiadapter mode (DX12) or Linked Display Adapter (LDA) mode through WDDM. BG3 might be able to do this on Vulcan, but BG3 on Vulcan also has some crashing issues at the moment, so I'd still recommend DX11 for stability.
On the hardware selection itself;
If you want to avoid custom water loops, I would probably go with this chassis instead: https://www.microcenter.com/product/660146/lian-li-v3000-plus-tempered-glass-eatx-full-tower-computer-case-black. It's extremely pricey, but it supports an inverted motherboard tray and has plenty of space for you to mount both radiators from the GPUs without the NH-D15 being in the way of your tubing. You can see the different configurations on Lian Li's website: https://lian-li.com/product/v3000-plus/.
Definitely looks like an interesting build though, wish you the best of luck with it.
Thank you so much for this! This was incredibly helpful.
I already have the lancool II, so I'd like to not get a different case. At your suggestion, I started going down the custom cooling rabbit hole, and am going to try to build a soft tubing loop with the Asus 4090 tuf + Corsair water block for it.
A couple of follow up questions:
Since this is my first build, I'm going to take advantage of the integrated graphics chip in the 13900k, setup the basic parts / cooling loop without the GPUs and then gradually add. The GPU to water block conversion is the part that on paper seems the scariest to me (although I'm sure there will be other scary moments I am not anticipating :) )
I made a rough sketch of the plan, getting stoked about it.
Thanks again for your help MichaelB!
If you are going the route of a custom loop, we can definitely make the Lancool II work. In fact, I'll give you a picture of a new test bench I just built in our lab for GPU testing:
This loop is designed for us to use quick disconnect fittings to add/remove hardware quickly so we can test both waterblocked and aircooled cards with minimum downtime.
Now to answer your questions;
As for the loop designs provided, I like your QDC placements, they should work fine. One issue I overlooked was the PCIe configuration of your motherboard. The bottom PCIe x16 slot is only wired for PCIe 4.0, and only x4, not x16. This might present a bottleneck in PCIe bandwidth as the slot is also wired to the board chipset and not the processir:
I can't find any details online as to whether or not the top PCIe slot supports PCIe lane bifurcation to split it into two x8 slots. This might be a challenge if you already have this board and are planning to get the most performance out of the dual 4090 configuration.
Some additional advice on the watercooling side of things. I would probably recommend foregoing the rear 120mm radiator. QDC fittings are already going to restrict the flow rate quite a bit. This coupled with using multiple water blocks will result in loss in head pressure. Both the modern DDC and D5 pumps offer a solid flow rate, but head pressure is often difficult to maintain. Instead, you could use a 120mm DDC pump like the one in my picture above, or use a 240mm D5 pump mounted above the PSU shroud.
Also, I know conventional wisdom states that slight positive pressure is better for a system, make sure every radiator in the loop is configured to exhaust. You do not want to dump hot intake air into the chassis, only for the second rad to pull that hot air in. Both being set to exhaust will result in better thermals, but at the cost of dust buildup in un-filtered areas of the chassis. Keep an ESD safe duster handy to clean every month or so.
Lastly, it might be worth considering using an external radiator since you are going with QDCs. You can run a 360mm + 240mm for gaming, then connect your loop to an external radiator for when you are running intense high precision operations on the GPUs. You can cut some holes on the back of the chassis add circular rubber grommets and run soft tubing out with a valve on them so you can swap seamlessly. I loved my old MORA3 radiator and it by itself could cool both your GPUs and CPU with relative ease. The thing was massive: https://www.performance-pcs.com/water-cooling/radiators/watercool-mo-ra3-420-pro-black-wc-25120.html
When done right, it can also look amazing too: https://www.youtube.com/watch?app=desktop&v=QXv1owX8zx4
That picture really helped me get a sense of the scale of the tubing/fittings! Ok making a couple of tweaks based on your reply.
So the new configuration would like this:
Hopefully last questions before I start ordering parts.
Those external radiators look really cool. I think I will try that when I get to adding the second gpu.
Just to recap the final parts round-up for single gpu build:
Also I was able to find all the parts at my local microcenter (Brooklyn, NY) except this: Corsair Hydro X Series XG7 RGB 40-SERIES GPU Water Block (4090 STRIX/TUF) doesn't seem to be carried. Do you think they would order it for me or will I have to purchase separately?
I think the MSI MEG Ace board is an excellent option. The VRM is insanely good and the trace layout makes it exceptional for overclocking if that is something you anticipate getting into in the future. This board also supports lane bifurcation, which is why it's able to switch from x16 to x8 to accommodate both GPUs.
To answer your questions in order;
As for getting that block special ordered, I don't know if that is something they can do, but you can always ask their management team. If it is in-stock at any of the other NY stores, they might be able to work something out, but I can't really guarantee this. Overall, your component selection looks fantastic and I think you'll be happy with the end result. It's always nerve racking to build a custom loop on the first time, but that feeling goes away once you get into the groove of it. I don't mind walking you through that process either, so feel free to reach out if you have any questions during the build.
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