RTX 4090 Max VRAM OC's

[555BUK]

So, I grabbed myself a 4090 FE and have been testing for the past 3-days. My intent was to find the max stable VRAM OC, and then drop power limit to around 70%/300W for 24/7 usage. Anyways, it has taken me much-longer than expected (for good reasons).

Many reviews say good cards can do +1500 on VRAM, with very-good cards doing +1600 or perhaps even +1650. None appear to show +1700 with stabilty.

Anyways, I started at +1200. All benchmarks (TimeSpy, Port Royal, Heaven, and games) passed with flying colours.
then +1300, all good.
then +1400, all good.
then +1500, all good.
then +1550 and +1600, all good.
Above +1600 I tested in +25Mhz steps. This started to get boring.
I have just completed all benchamarks plus nearly an hour of Starfield @ +1900. All-stable. Not as single glitch, error or crash since the day I started. There may even be a few MHz left in the tank.

So, who else has gotten to +1900 VRAM OC or behond on stock cooling?

Please post you card and clocks.


Links to my 3DMark benches @ +1900 below.
Port Royal Time Spy Time Spy Extreme

Edit: After a another long test session, +2000 is looking stable.

 

[555BUK]

Any ideal what % fps this would add to a game ? thx

Not played many games yet, however Starfield jumps about 3-4 FPS (mid-70's to 80'ish) on max settings. F1 2023 only gains a few percent, however this game is CPU-limited @ ultra-wide resolution. Benchmarks show around 5-6% gains. I don't think the 4090 is memory bandwidth limited, so gains will be small without corresponding GPU horsepower/OC. Gains may be bigger @ 4K res.

The real benefit of the VRAM OC is that it allows dropping core voltage / GPU power draw massively whilst keeping stock (or slightly-better) performance.

 

[555BUK]

It has built in error correcting so is unlikely to crash or give errors unless it's pushed past that point
If you push it too far performance will start to drop

Indeed. That's why I take so-much time and run multiple benchmarks at every increment. So far, every little bump has shown small gains.

I also had a Zotac 4090 for a few days. It had some fault whereby the GPU (at stock) would randomly downclock to 300MHz and stay there (even after restart). It got returned, however when it worked that cards VRAM would only reach ~1350MHz before massive screen tears. It may depend upon whether the memory or memory controller has reached its limit, as to if the card starts error-correcting or displays tears/corruption.

 

[555BUK]

Well, +2000 VRAM is looking stable. All benchmarks pass with (slightly) higher scores than +1900, jumping between games for ~2-hours has been fine. Even Doom Eternal with it's stupid-high FPS has been fine, and this is the one which has typically failed first during testing of my previous GPU's.

To be fair, there is very-little difference between stock VRAM, +1000, +1500 and +2000, but every-little bit is free. I would love to know what VRAM IC's are on this card, but I ain't popping it open will remain a mystery.

I absolutely love this FE card. I just have to ensure the wife doesn't discover how much it cost.

 

[555BUK]

How far does your Fe core clock to? mine hits wall at 3015 anything over crashs. max voltage goes up to 1.070. am sure previous 4090 fe can hit 1.1 volts?

Zia

I hadn't really pushed the core yet. I have a small Meshify C case and a 850W (but very-very decent) PSU. My intent was to undervolt the core to less than 300W average load. Currently I am liking Power Limit @ 70, VRAM @ +1500, core @ 950mv. At these settings power draw averages about 270W within the games I play, however performance is pretty-much identical to stock.

For the benefit of science, I just played Starfield and Doom each for 10-15 mins @ +260 core / +1500 vram on stock volts, and all looked good. I'll run some benches and test more later, but it's too-early to tell if 3000MHz core is stable yet. Within Starfield & Doom 3000MHz boost is maintained using stock volts.

Edit: Scrap my last comment. Port Royal crashes at 3000MHz on stock volts. More tinkering needed.

Edit2: +260 core / 3000MHz appears stable running everything EXCEPT Port Royal. Time Spy, Time Spy Extreme, Heaven, Doom Eternal, Starfield, Jedi Survivor, F1 2023 all run fine. It is just Port Royal that crashes to desktop when anything over +200 is applied.

So, +200 core (2940MHz) is stable for everything.
and +260 core (3000Mhz) would be stable if not for Port Royal benchmark.

I think Port Royal must really stress those RT cores. It would be interesting to know if others who can hit 3000MHz core are Port Royal stable?

 

[555BUK]

Are these results with 4 pcie cables used from your power supply to your FE that equals 600w or just 3 connected 450w ? or don't the FE have that option, thx

My PSU is a vintage 2009 Corsair HX850W. I purchased an official Corsair 12VHPWR power cable compatible with this PSU, so 600W is fully-supported despite the PSU being 14-years old and only rated for 850W. This unit has run multiple SLI/Crossfire (remember those) setups in the past without issue - and the 12V rails are rock sold.

As the PSU is 850W and my case is small, I am sticking to a max PL of 100% for testing. I am now pretty-certain 24/7 clocks will be core @ stock (2720MHz boost), Power Limit @ 70%, VRAM @ +1500, 950mv undervolt. That gives a max power draw of 315W whilst providing ~100% of stock performance.

I'll leave 3000MHz core and +2000 VRAM for occasionmal benchmarking, as the OC makes little difference for gaming. The VRAM OC @ 1500 adds almost nothing to power draw. Any core OC starts sucking disproportinate ammounts of power.

I am extremely-happy with the card. The memory OC is god-tier, the core OC is very-good (superb if I ignore Port Royal @ 200+), coil whine is minimal, plus when undervolted it provides monsterous performance whilst sipping the power. It is better than I had hoped for.

 

[555BUK]

Thx for reply, so because you are using 600w input, i guess that means you can go over the 100% slider i see people talking about, as if i only have 3 x pcie connected, that limits me to just 450w and cant overclock core correct ?

You can still OC the core, however you'll be limited to max 450W GPU power draw. Most games will not get close to pulling 450W anyway, however benchmarks such as 3DMark Port Royal will reach the limit, and will begin to pull-back boost clocks.

With a 600W 12VHPWR cable, the power limit slider allows upto 133%.
With a 3x PCIE to 12VHPWR splitter, only 450W / 100% should be available.
It also depends upon individual graphics card BIOS. Some lower-spec 4090's only allow 450W even if a 600W 12VHPWR (or 4x PCIE to 12VHPWR) connection is made.

In all-honnesty, going above 450W will yield next to no performance gains on air or water cooling. The only gains will be more heat and higher power-consumption. That's why I am aiming for low-power rather than high. Keeping GPU power low allows all of the system to run cooler and quieter.

 

[555BUK]

Thx, yes i will only be using 450w when i build my new PC, got most parts now, just deciding on a PSU.

Go for a minimun 1000W PSU. When I purchased my HX850W it was massive-overkill for the time. 14-years later it is still going strong, and comfortably powering the fastest consumer GPU, plus one of the fastest CPU's currently availaible. You can never over-spend on a PSU. A good one will far-outlast every other component within the system. For reference, my Graphics Card at the time was a Radeon HD 5850 with a massive 1GB VRAM.

 

[555BUK]

Right, 3000MHz core @ 1070mv has been stable with everything I have thrown at it except Port Royal. Port Royal doesnt like anything above 2950MHz core on my card/system. Perhaps throwing more volts at it and increasing the power limit will help, however this will be of zero benefit for me as I am hunting the best low-power/high-performance compromise. I think hunting Port Royal stability at or above 3000MHz will be behond my card, and most air-cooled 4090's. Sure, I could get a few lucky-runs in, but that's not stable.

+2000 on the VRAM has been completely stable on everything.

However, 3000MHz AND +2000 VRAM will not play together. One starts detracting from the other, and I see glitches.

3000MHz core AND +1900 VRAM does seem stable on everything (except Port Royal). I have just done an hour on Starfield without any issues. It also passes all other benchmarks.
2900MHz core AND +2000 VRAM also looks stable on everything, including Port Royal.

I think that's the end of my tinkering for awhile.

 

[555BUK]

Within my benchmarking, a 10% core OC and a 17% VRAM OC results in an average +7% versus stock. I only have a Ryzen 7950X CPU. One of the X3D's or 13900's may show larger gains.

Here's a Time Spy Extreme compare showing stock vs 3000core / +1900vram.

In-summary, for most people it's not really worth overclocking these beasts - they're already phenominal. You'll only gain a few FPS at the cost of ~30% more power and heat.