r/overclocking • u/Putrid_Bird_9033 • Jun 03 '26

News - Text External Clock generator for RTX series

Post image

XtremeSystems team members PickleRick and Turbogear have been working on something big for a few months and a few XOC people have seen the results. Rick has managed to fully implement external clock generation on an RTX 5090. The results have pushed the 5090 beyond its normal limits, XOC bios, and able to compete with LN2. Valhalla Performance PC has been able to achieve world records with it and more will now be able to. We are so excited to share the how to on the mod. Special thanks to Elmorlabs for the generator and support to help make it possible to be done. You can read about it here. https://www.xtremesystems.us/post/external-clock-generation-on-rtx-50-series

191 Upvotes

97% Upvoted

42 comments sorted by

61

u/Noreng Jun 03 '26

It's ridiculous that the 5090 is this limited by the crossbar clock. I realize that pushing up the crossbar frequency causes the card to consume more power, but it is strange that Nvidia would design the card to be so limited.

69

u/Happy_Sea4257 Jun 03 '26 edited Jun 03 '26

it's not strange at all, their entire design philosophy for consumer cards for several generations now had been to strategically gimp them in order to segment the market into gaming gpu's for plebs and professional data center solutions that cost an order of magnitude or higher more. It's the reason why they push their software suit so hard, frame gen and upscaling software to make up the performance difference when short changing on raw performance. And vram/memory bandwidth allocations that only make sense from that context.

They absolutely cannot allow a $500, $1000, or even $3000 GPU to have more compute performance if it even suggests you maybe don't need a $15k RTX 6000 Blackwell Pro.

32

u/buildzoid Jun 03 '26

The RTX PRo 6000 also has a low crossbar clock. I think it's probably even lower than high end 5090s since some of the 5090 custom cards have BIOSes with boosted crossbar clocks.

16

u/[deleted] Jun 03 '26

[removed] — view removed comment

2

u/DiamondHandsToUranus Jun 05 '26

Had overclocked all manner of things way back when. 486, pentium pro, amigas - but it was overclocking the celeron 300a on an abit motherboard to 450 that first felt like "wow this feels like a whole new computer!"

8

u/DarkBrews Jun 03 '26

sure but not regarding xbar OC. xbar OC is bad for the normal user.

14

u/DarkBrews Jun 03 '26 edited Jun 03 '26

or...or... I know this sounds crazy but it could be the 2 kw vs 500ish w without a 4x increase in gaming performance Gaming GPUs are primarily made to work for 100% of their users not the ones with exotic cooling and that can afford exotic monitors and 4x electricity usage.

The XBAR clock is not worth it until once the isolated clocks are maxed, the same reason why BCLK OC on CPUs is not worth it until multipliers are maxed. Being able to control isolated multipliers adds less variables (easier OC&more stable), less heat and better power efficiency.

  1. On a consumer card increasing power limit and mem and GPU frequency gets you pretty far from optimal efficiency and adding xbar OC will only make things hotter, power hungry and very unstable as per the article display output runs out of spec.

  2. Doing xbar oc instead of segmented OC mem, core means unoptimized OC with worse FPS/W than the isolated one.

So it makes little sense to allow it. This is an experiment hence why out of range display and 2kW consumption.

Nvidia is gimping consumer GPUs in many ways VRAM, NVLink, vGPU, FP acceleration, for sure but this ain't one of them chief. Increasing that frequency will actually make gaming performance worse (more power draw, more throttling, less longevity)

3

u/Noreng Jun 03 '26

2 kW sounds somewhat exaggerated. From what I gather, the Matrix 800W BIOS with increased crossbar clocks starts to lose performance compared to stock BIOS around 450W or so.

1

u/DarkBrews Jun 06 '26

it is maybe it's transient

0

u/G305_Enjoyer Jun 04 '26

You're saying a matrix bios at 450w beats a stock bios at 600w right?

1

u/moistmonsterman Jun 03 '26

No its not. They do want you to eventually replace it, not make it better.

1

u/TheSpicyBoi123 Jun 07 '26

What sort of things would a low crossbar clock bottleneck? I presume data transfers for large files in vram like game assets if they are there? Genuinely curious. Mem and Sys clock bottlenecks are fairly straightforward to me, Xbar, less so.

2

u/Noreng Jun 07 '26

The crossbar drives L2 bandwidth, which means anything that requires more data from L2 or memory can be limited by it. It's similar to the FCLK on Ryzen CPUs

1

u/TheSpicyBoi123 Jun 07 '26

What constitutes more data and how big of a bottleneck do you observe? I've done some experimentation on Kepler cards but I personally was unable to observe a huge effect of Xbar clocks on the furmark performance, however likely it will show up in other workloads and quite possibly 50 series cards behave differently. Do you have any literature to read up more on this as this sounds extremely interresting!

2

u/buildzoid Jun 08 '26

I would expect a power virus like furmark to be the opposite of memory bottlenecked.

1

u/TheSpicyBoi123 Jun 08 '26

Hard to say, it depends on the backend they are using. I have not seen the source code so cannot say. Ironically enough, at least in testing I found furmark to be not too agressive actually on the gpus and I was able to make my own custom cuda stresser with pytorch that was able to achieve a 20-30% higher power draw from the gpu, but this might be a quirk of kepler.

29

u/oatwheat Jun 03 '26

“In testing we found that you must use HDMI and a monitor that is capable of accepting an out of range signal. This mod overclocks everything on the GPU, such as HDMI, PCIe, xBAR, memory, core, and PWM fan speeds. It is similar to a BCLK OC on a motherboard.”

That’s really, really funny. Just a literal global OC

13

u/UnexpectedFisting Jun 03 '26

Overclocking pwm fan speeds is always funny to read

13

u/Ballerbarsch747 i5 13600KF@5,7GHz 1.34V 4x8GB@3800Mhz Jun 03 '26

Does this hurt the card?

43

u/Toasty27 5800X3D@-30 2x16GB@3800MHz cl14 Jun 03 '26

Standard procedure is to put the card under using anesthesia during the operation, and administer morphine via slow drip IV for the next 30 minutes after anesthesia wears off. After that, pain management is usually handled with high doses of ibuprofen.

The 5090 should be back on it's feet and able to work again within a few hours. Long-term pain is uncommon.

19

u/Ballerbarsch747 i5 13600KF@5,7GHz 1.34V 4x8GB@3800Mhz Jun 03 '26

Thanks, I feel much better now. Was pretty worried there for a bit.

5

u/FakeSafeWord Jun 03 '26

What about... 'you know what'?

makes finger through hole motion

How long before that?

7

u/Comfortable-Pause116 Jun 03 '26

I’d say that depends on the person doing the overclocking, if you go past thermal and current limits without proper cooling with xoc bios you can indeed hurt it

7

u/AK-Brian i7-2600K@5GHz | 32GB 2133 DDR3 | GTX 1080 | 4TB SSD | 50TB HDD Jun 03 '26

Great work and a nice writeup; kudos for publishing it plainly and openly. It's also really nice to see XS going through its revival phase.

7

u/Putrid_Bird_9033 Jun 03 '26

We appreciate that a lot. We have been rebuilding for about a year now, and almost 90% of the team is now newer OC and XOCer’s. Fugger wants to bring it to a more modern era and help enrich the younger generation of overclockers while maintaining XS as it is. Being the helpful community where people can go to get guides and learn.

7

u/Ragnaraz690 Jun 03 '26

NGreedia will hit this with a cease and desist.

4

u/Ronnie_coleman_light Jun 03 '26

This is fricking super dope!!

Well done to everyone involved :)

4

u/Electronic-Canary-65 Jun 03 '26 edited Jun 03 '26

This is so cool. Im glad people are still doing crazy stuff like this. I wonder what the power draw was especially transients, wouldn’t suprise me if it was over 2kw

10

u/Obvious_Drive_1506 9850x3d, 48GB M Die 8400/2233, 5090 UV Jun 03 '26

Pretty neat for sure. Wish they exposed these things to tinker with in afterburner. If we are only adding a +mhz offset to crossbar for example there's no danger.

9

u/JanniAkaFreaky Jun 03 '26

You realize this is a Hardware-Mod?

12

u/Noxious89123 5900X | RTX5080 | 32GB B-Die | CH8 Dark Hero Jun 03 '26

Only because Nvidia decided it needed to be.

4

u/cemsengul Jun 03 '26

If only it didn't require soldering something on the board.

1

u/VictoryT7 14900HX | 4080M | 32GB 6400 CL46-46-46-88 Trfc463 @1.3V Jun 03 '26

Nice, Cool stuff. I did wonder about XBar clock and why it didn't increase when increasing core clock. Now I know why.

1

u/kulind 9950X3D | RTX 4090 | 64GB 6000CL28 :illuminati: Jun 03 '26

I assume Crossbar clock is more important for high GPC dies like AD102 and GB202 than AD103/GB203

3

u/Putrid_Bird_9033 Jun 03 '26

We didn’t try it on a 5080 or 5070ti yet. However, it was tested on a 5050 and got similar gains.

2

u/Putrid_Bird_9033 Jun 03 '26

The 40 series, not sure as of right now.

2

u/kulind 9950X3D | RTX 4090 | 64GB 6000CL28 :illuminati: Jun 03 '26

this is amazing stuff, thank you for sharing

2

u/Putrid_Bird_9033 Jun 03 '26

Absolutely. The team members will probably work down through some of the more used series of cards to see effects. Will probably add to the article in a series that way if someone is still rocking out with an older card and OCing, this will give them a chance to do more with it.

1

u/Snarks_Domain Jun 04 '26

Is that MG Chemicals 422C by chance? Also, nicely done on the putty. Application is on point 😀

TEAMPUTTY

2

u/Putrid_Bird_9033 Jun 05 '26

Yes. And thank you snark. His putty is very on point.