13900KS + RTX4090 Build Notes

[Bob Scott 7,721]

Here are some thoughts and a few lessons-learned from my recent build (specs in my sig):

RTX4090 size--make sure the card fits in your case.  My ASUS TUF Gaming 4090 is 14 inches long, and was too long to fit on the mobo without hitting the drive cage on my full-tower Coolermaster HAF-X cases. Additionally, the card is 7 inches high off of the motherboard, and the PCIe5 power connector requires a good 2.5 - 3 inches clearance to the side cover to allow for a reasonably gentle bend in the heavy power cabling without imposing a lot of side stress on the flimsy connector.  Whoever designed the geometry of the connector apparently has never actually built a PC...it's a really thoughtless design flaw.  CableMods is apparently designing a series of 90 and 180 deg adapters, but they've been delayed and still aren't available.  So make sure your case is both deep and wide enough.

Airflow with the gargantuan 4090 in the case bears some extra thought--the 4090 essentially partitions my case into an upper and lower half due to its size, and in the lower half below the GPU there is a pocket where there is little to no airflow unless the GPU fans are running and pulling air up.  I noticed my PCH temps were really high, even at idle (~80 deg C), so I removed the side cover and put a small fan outside blowing into the case, and saw a 20-25 deg drop in PCH temps.  Unless you have a side-panel mounted fan, most cases do not push much air around the bottom half of the case.  And the air coming off the GPU under load is really warm--my IR thermometer gun says around 40 deg C, so some attention to removing that hot air rather than redirecting it into the case is important.

The Intel i226-v LAN chip installed on many Z790 motherboards has just been discovered to have a serious flaw (much as its predecessor the i225-V did) that causes the ethernet connection to drop momentarily for ~3-5 sec at random times.  There is no fix yet.  It wreaked havoc with my P3D remote apps, like Radar Contact, ActiveSky P3D, LittleNavMap etc.  I can't imagine how much fun that'd be with MSFS, with its dependence on uninterrupted streaming scenery.  Deselecting the "Allow Windows to turn off this device to save power" in the OS, and turning off the EEE (Energy Efficient Ethernet) and hard-selecting 1Gbps in the device settings seems to have at least reduced the frequency.  Most high-end boards that use this network chip also have built-in WiFi, and possibly a second non-Intel LAN port.  If not, then a USB-to-Ethernet LAN adapter is a fairly inexpensive solution to Intel's incompetence.  With Z790 boards running well north of $500 this is utterly inexcusable.

The 13900KS is a top-binned 13900K...I've been able to reliably run P3D with the main core overclocked to 6 GHz (even to 6.2 GHz with uncomfortably high voltages), the rest of the P-cores at 5.8, and the e-cores at 4.5.  The 13900K + Maximus Z790 is extremely flexible w/r/t the ability to independently overclock specific cores, shut off cores etc.  Paired with P3Dv5's new affinity mask settings, you can put the all-important main thread on an overclocked single core without forcing the rest of the chip into a (figuratively speaking) meltdown by trying to run the other 23 cores at the speed of heat (not figuratively speaking).  I'm still tinkering with the pros and cons of P3D with varying core configurations.  The flexibility is proving to be powerful good magic, though.  The TVB (thermal velocity boost) feature really works well to dynamically increase clock speeds when the temps permit.

I've turned off hyperthreading on this CPU--the OS prioritizes thread assignments to the P-cores first, then the e-cores, then the HT virtual cores.  With 24 physical cores, I can't see how forcing the P-cores to share resources with a virtual CPU sitting at 25th-32nd on the priority list does anything but produce more heat and dilute access to cache.  If 24 cores aren't enough, HT isn't going to help much, if at all!

No two ways about it--the 13900K is a heat monster.  You can reduce the thermal output a fair bit by shutting off cores in the BIOS, and by running at lower speeds.  But plan on an aggressive cooling solution, or maybe go with a lesser CPU if that's not possible.  I'm running two 360mm radiators in series and half-inch diameter water tubing, and I can still hit thermal throttling without trying too hard.  The real limfac is the challenge of transferring a lot of heat off of the relatively small surface area of the CPU package.  I wouldn't think it likely to reap the full benefits of the CPU without at least a good 360mm triple-fan AIO unit.

Power supply requirements--with a moderate stress test like RealBench 2.56 running on all-cores at stock speeds (5.6/4.3 GHz) I see 800W at the wall.  My best working overclock (60x1 58x7 45x12 43x4) pulls 950W at the wall under load.  Typical sim loads are 350-500W--more if the GPU is cranked-up (e.g. dynamic lighting and SSAA).  Do not even think about going cheap on a PSU with a 4090 in the case.

I was pleasantly surprised to find the Memtest 86+ memtest utility is now built right into the BIOS on the ASUS Maximus Z790 boards.

For anyone building with the ASUS Maximum Z790 Hero, the 0813 BIOS proved golden w/r/t memory compatibility.  My 7800 MHz GSkill DDR5 kit wouldn't POST at XMP speeds with the BIOS shipped on the board, but it worked immediately at XMP without any fiddling at all with the new BIOS and the "XMP Tweaked" settings built into the new BIOS.

That's about it.  It's a rocking good combo if you're looking for a high-end upgrade.

[rickjake 243]

37 minutes ago, Bob Scott said:

 

The Intel i226-v LAN chip installed on many Z790 motherboards has just been discovered to have a serious flaw (much as its predecessor the i225-V did) that causes the ethernet connection to drop momentarily for ~3-5 sec at random times.  There is no fix yet.  It wreaked havoc with my P3D remote apps, like Radar Contact, ActiveSky P3D, LittleNavMap etc.  I can't imagine how much fun that'd be with MSFS, with its dependence on uninterrupted streaming scenery.  Deselecting the "Allow Windows to turn off this device to save power" in the OS, and turning off the EEE (Energy Efficient Ethernet) and hard-selecting 1Gbps in the device settings seems to have at least reduced the frequency.  Most high-end boards that use this network chip also have built-in WiFi, and possibly a second non-Intel LAN port.  If not, then a USB-to-Ethernet LAN adapter is a fairly inexpensive solution to Intel's incompetence.  With Z790 boards running well north of $500 this is utterly inexcusable.

 

Nice build Bob. 

I built a new computer over the Christmas holidays very similar to yours, with all the same issues and concerns. Was pulling my hair out, trying to figure out why I was getting very long pauses In VR and non-VR at all phases of flight on MSFS. It wasn't until a poster here on AVSIM, pointed out the flaw in the Z790 i226-v LAN chipset that directed me to a solution. Once I put in an PCIe Network card in, did it solve my issue. I agree, this is unacceptable for a very expensive motherboard.

I was not able to get my ram to run at XMP speeds at all without tweaking it. But I also have 4 sticks which adds to the problem. I was able to get XMP running stable at 6400 instead of the 7200 I paid for. Before the last BIOS update, I could get 6000 stable.

I agree, its a heat monster.  I run mine with a 460mm AIO and can still easily hit 100c 

[Ted Striker 338]

Fantastic post there Bob. Very well written and a wealth of information you rarely see even on "professional"  hardware review sites.

Ted

[penta_a 429]

3 hours ago, Bob Scott said:

That's about it.  It's a rocking good combo if you're looking for a high-end upgrade.

thanks for this very informative and detailed report.

I have acquired following parts so far;

- Corsair 7000d case.

- Corsair 1500w PSU

- EK-Nucleus AIO CR360 Lux D-RGB CPU cooler

- 1TB M.2 Samsung 990 Pro

- 2TB M.2 Samsung 990 Pro

- ASUS TUF RTX 4090

 

and waiting on review results of the upcoming AMD 7900X3D and 7950X3D to choose the right combination for me (MB+CPU+MEM), either BLUE team or RED team based on final verdict from approved reviewers.

[Bob Scott 7,721]

3 hours ago, penta_a said:

thanks for this very informative and detailed report.

I have acquired following parts so far;

- Corsair 7000d case.

- Corsair 1500w PSU

- EK-Nucleus AIO CR360 Lux D-RGB CPU cooler

- 1TB M.2 Samsung 990 Pro

- 2TB M.2 Samsung 990 Pro

- ASUS TUF RTX 4090

 

and waiting on review results of the upcoming AMD 7900X3D and 7950X3D to choose the right combination for me (MB+CPU+MEM), either BLUE team or RED team based on final verdict from approved reviewers.

I started with three 2TB Samsung 990s and didn't even get them out of the box before swapping them for the WD SN850X--there was a breaking issue reported where the health status on the drives was dropping precipitously with little usage.  A firmware update to fix that just came out in the last 24 hours--make sure you update the firmware on your 990s first thing after you install them.

https://www.tomshardware.com/news/samsung-990-pro-firmware-update-released-ssd-health

 

 

[penta_a 429]

2 hours ago, Bob Scott said:

-make sure you update the firmware on your 990s first thing after you install them.

https://www.tomshardware.com/news/samsung-990-pro-firmware-update-released-ssd-health

 

 

will do, many thanks for the heads up.

[regis9 4,014]

Lots of great advice there Bob.

Sounds like a fantastic build, enjoy!

[micstatic 4,319]

Nice write up Bob.  I'm sitting on a 4090 (founders edition).  But been waiting to install it until the cable mod 90 degree adapter is ready.  Hoping that it fits.  Because if it doesn't, I'm going to have to get a new case and rebuild.  Obviously that is not something I'm looking to do.  Time continues to be my enemy...

[odourboy 1,289]

28 minutes ago, micstatic said:

But been waiting to install it until the cable mod 90 degree adapter is ready.

Me too, but I didn't wait. I'm just running with the side panel off.

[Bob Scott 7,721]

3 hours ago, odourboy said:

Me too, but I didn't wait. I'm just running with the side panel off.

I'm currently doing the same...I'm going to end up custom-building a replacement side panel with a 230mm fan to keep the lower half of the mobo cool and provide a direct path out for the hot GPU exhaust.  The glass panel that came with the case just isn't gonna hack the program.

I am soooooo deeply frustrated that the build didn't fit into one of my HAF-X/HAF-932 cases.

[odourboy 1,289]

10 minutes ago, Bob Scott said:

I'm going to end up custom-building a replacement side panel with a 230mm fan to keep the lower half of the mobo cool and provide a direct path out for the hot GPU exhaust

I like that idea!

[jt_williams 291]

On 2/13/2023 at 6:09 PM, Bob Scott said:

A firmware update to fix that just came out in the last 24 hours--make sure you update the firmware on your 990s first thing after you install them.

Bob,

Thank you for this timely announcement.   I configured my new flightsim rig with three 990's.   I did a health check and they were all OK.   I have just completed the firmware update.  Hopefully this fix sticks.

Jeff

[odourboy 1,289]

Got tired of waiting for CableMod so I ordered one of these:

https://www.moddiy.com/products/ATX-3.0-PCIe-5.0-600W-12VHPWR-16-Pin-90-Degree-Angled-Extension-Cable.html

[westman 257]

nice Bob

my 4090 is only 11inch long and 2 inch tick it fit my Fractal and the temps is ok.

system is custom watercooled Mora 420 ( same as 3 420 rads 4x 200 noctua fans) outside chassi 

gpu is hybrid cooled water and air , home brewed.

powercables from cablemods 600W with 3 eightpin connectors.

https://www.dropbox.com/s/n8mwvuupsw2tk4i/20230122_145658.jpg?dl=0

Gpuz power read is 180W its wrong it should be 360W , gpuz only read one of the pwower connectors 

https://www.dropbox.com/s/axeu7u8vny2h6qg/MSFS2020-gpuz.jpg?dl=0

Edited February 17, 2023 by westman

[Ray Proudfoot 8,960]

I appreciate this is an older topic but still very relevant for those of us lucky enough to afford the CPU and GPU mentioned.

My own computer was professionally built by Chillblast here in England. It has a i9-13900K with HT enabled. That was how it was delivered by Chillblast.

When flying the PMDG737 and FSL Concorde I see the CPU temp frequently reach 100°C before the fans kick in and it then drops back. But the cycle is repeated and I can’t think this is a good predicament.

I’m using RTSS to monitor all 24 VPs and it’s clear most are being used hence the reason for the high temps I guess. @Bob Scott has disabled HT on his and that’s something I would like to do. According to this shot of my BIOS it’s just a case of turning it off.

My next question is how many VPs would that leave me with and how best to configure them given I’m not an expert in this area. According to Intel’s site for the 13900K it has 8 performance cores, 16 efficient cores and a total of 32 threads. Am I correct in assuming those 8 performance cores double to 16 with HT enabled? So those 16 + 16 efficiency cores = 32 overall.

If I turn off HT what am I left with and how best to configure the BIOS. Thanks for any help.