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How I Overclocked the Ryzen 9 3900XT to World-Record Speeds

AMD’s Ryzen 9 3900XT has been out for a little now, and due to COVID-19 (I’m an everlasting optimist), I’ve had abundant time to mess around and spot what is going on with those new, high-frequency chips. I even controlled to snag a couple of global overclocking data for the Ryzen 9 3900 XT alongside the way in which.

When I used to be first requested if I sought after to take a look at those new chips out, I figured, ‘meh.’ There doesn’t appear to be a lot distinction between the X and XT fashions, and AMD most certainly simply makes use of upper voltage and greater the turbo multiplier on a couple of cores. I’ve been incorrect various occasions, and I used to be once more: The Ryzen 9 3900XT CPUs are cherry silicon. 

At the time of writing, the 3900X is $429 and the 3900XT is $479. That method you’ll be able to have upper turbo clocks and higher overclocking capacity for more or less the price of going out for a steak dinner (which you’ll be able to’t do presently; thank you once more, COVID). AMD truly made a smart decision right here. The efficiency building up is simply sufficient to fulfill us overclockers, however now not such a lot as to anger new 3900X house owners. Meanwhile, AMD makes some further income on what is basically a super-binned Ryzen 9 3900X.  

(Image credit score: Tom’s Hardware)

 Real World Overclocking 

I used the similar parts for real-world checking out that I used for liquid nitrogen, however tapped the Enermax Aquafusion 3x120mm AIO for cooling. With my CPU already having been flattened (aka lapped), I sought after to test the outside of the AIO to verify it was once first as neatly. 

(Image credit score: Tom’s Hardware)

As you’ll be able to see, it appears to be like nice, great and flat!  

(Image credit score: Tom’s Hardware)

I have a tendency to strictly want the efficiency facet of items, so aesthetics aren’t truly in my realm of attention. The cooler does a super task of dealing with the 1.4V I fed to the core at 4.55ghz via more than one loops of Cinebench R20. Temps reached the mid-80C’s. 

(Image credit score: Tom’s Hardware)

The LED wattage show at the Maxtytan PSU confirmed that overall machine energy utilization clipped at simply above 300W throughout the benchmark. That’s lovely low for a maxed-out overclock on 12 tough cores. 

(Image credit score: Tom’s Hardware)

I’m partial to fastened frequency, so I all the time lock my chip into the very best all-core clocks I will get, even on my daily-use pc. These chips run lovely cool for 12 cores, so fan noise, and so on., isn’t truly an issue. In this example, you’ll be able to see that I hit 4.5 GHz always on all cores with none problems. 

Pretesting for Ryzen 9 3900XT World Records  

(Image credit score: Tom’s Hardware)

As we all know, you’ll be able to make some attention-grabbing efficiency improvements with AMD processors by way of optimizing all of the other multiplier ratios, together with the reminiscence, UCLK (reminiscence controller frequency), and FCLK (material frequency). 

Many benchmarks, particularly ones that want reminiscence bandwidth, reply neatly to a 1:1:1 ratio for those three key settings. For instance, you need to dial in an 1800 MHz material, DDR4-1800 reminiscence and 1800 MHz UCLK. If we raised our reminiscence frequency above our material clock, as an example, surroundings an 1800 MHz material and DDR4-2000 reminiscence, our UCLK would drop to 1000MHz, halving the reminiscence frequency. UCLK is the reminiscence controller frequency, so halving it may possibly create an potency drawback when benching. 

The material most often faucets out between 1800-1900 MHz with standard ambient cooling, because of this our optimum reminiscence frequency is 1800-1900 MHz. On liquid nitrogen, I hit the material restrict (sooner than the chip fails to serve as) at 1600 MHz, because of this a 3200 MHz overall DDR4 frequency. That is lovely low within the grand scheme of items, which is tragic as a result of AMD has a strong built-in reminiscence controller (IMC). This gave me an concept.

Dual Rank vs Single Rank Memory on Ryzen 9 3900XT 

I determined to take a look at some previous double-sided B-die reminiscence I had sitting in a drawer. Double-sided reminiscence could be very aggravating to the IMC, and thus it struggles to push excessive frequency in comparison to its single-sided brother (3933 MHz vs 4666 MHz). On the opposite hand, double-sided reminiscence turns out to run tight latency without a problems – it if truth be told runs the very same timings as single-sided. 

As a outcome, I will change the reminiscence from 16GB to 32GB with out even clearing CMOS and it is going to run absolutely solid. The x265 4K benchmark, which makes use of AVX and could be very delicate to reminiscence on AMD platforms, features a great deal from dual-rank DMMs. In this example, I received an additional 1 FPS, which is set a 7% efficiency building up within the apples-to-apples check.

(Image credit score: Tom’s Hardware)

This would possibly not appear to be a lot, however each and every little little bit of potency makes lifestyles that a lot more straightforward while you move to sub-ambient cooling. My chip isn’t the most efficient available in the market, however with a large number of pretesting and potency tweaks, it offers me a possibility to take hold of some gold medals. 

On a every single day use gadget, I might utterly suggest lower-frequency double-sided reminiscence over fancy high-frequency single-sided reminiscence.

LN2 Overclocking the Ryzen 9 3900XT 

My reminiscence is tuned and my working methods are tweaked, so it is time to pour some liquid nitrogen. My rig had the next specifications:

(Image credit score: Tom’s Hardware)

These CPUs wish to be as chilly as conceivable. My material restrict at -192C is 1,600 MHz, and bumping up the material isn’t an choice – even 1,633MHz creates a restrict at -150C. If I’m going less warm than that, the chip stops functioning. This isn’t optimum, however there are definitely worse chips available in the market. Some chips even fight at sub-1,500 MHz. 

The subsequent step is to set a tight core voltage. I began at 1.60V. Then, I greater the CPU frequency in 50 MHz steps. After it was once all mentioned and achieved, the chip ran at 5,650 MHz for x265 4K, and 5710 MHz for Geekbench 3. That was once sufficient to clinch the document for every bench.

(Image credit score: Tom’s Hardware)

Dual rank DIMMs truly gave me the brink in X265, whilst Geekbench turns out to favor upper frequencies for its reminiscence checks. The ASRock X570 Aqua ran the G.Skill TridentZ RGB single-sided sticks at just about 4700 MHz, and with very tight timings, too.  

Bottom Line

(Image credit score: Tom’s Hardware)

AMD’s Ryzen 9 3900XT is a frequency beast. There are various LN2 effects on hwbot.org that display that many 3900XT’s are operating upper clocks than the most efficient 3900X’s. It can be truly cool to look a 16-core Ryzen 9 3950XT, or possibly even a Threadripper XT type (yeah proper), however both method I believe the highest finish of the Ryzen 3000 sequence offers us a little bit little bit of a glimpse of what we will be able to see with the 4000 sequence. 

Hopefully AMD brings extra frequency in conjunction with an building up in instruction-per-cycle (IPC) throughput. It would even be great to look extra reminiscence producers push high-end, twin rank B-die reminiscence even additional sooner than we transfer directly to DDR5.