When we compared AMD'south latest flagship Ryzen ix 3900X caput to head with the Core i9-9900K in 36 games we found that on average the 12-core AMD processor was about 6% slower in gaming tasks. There were a few select titles where the Ryzen processor came out on tiptop, but for the near part it was merely a piddling slower.

Overall it'due south withal a practiced showing for third-gen Ryzen as the deficit when gaming is negligible for the most role, while it pummeled the 9900K in all productivity tests.

After we published that feature, nosotros've been requested by readers to retest the 3900X with SMT disabled, substantially turning the 12-cadre, 24-thread CPU into a 12-core, 12-thread CPU. Many say this can significantly amend gaming performance... only why?

We were instantly skeptical as we spent quite a scrap of time testing outset generation Ryzen with and without SMT and even back in 2017 the gains were not great and often you'd see a performance regression -- in other words SMT was doing what it was supposed to with no major downside.

Since Ryzen'due south introduction, Windows and gaming titles have evolved to back up the multi-core processors better, and our recent testing has found SMT to exist effective when information technology comes to gaming performance, on both Intel and AMD platforms. With that, we haven't tested the Zen 2 chips with SMT disabled and then we're going to go for it, even if we'thousand expecting to find the same every bit before.

For this test the Ryzen 9 3900X has been configured in its out of the box trim, using the Wraith Prism RGB box cooler. Both the SMT on and off configurations are otherwise identical.

Benchmarks

First up we have Prey and hither we see an impressive 9% improvement for the average frame rate with SMT disabled. Even more impressive was the 13% boost we saw for the 1% low result. The difference confronting the 9900K was macerated considerably even though the Core i9 was nevertheless the faster chip.

Just Cause iv also sees a very noteworthy 8-10% performance uplift with SMT disabled and that sees the 3900X shut in on the 9900K once again.

Testing with StarCraft Ii shows no improvement in operation with SMT disabled when looking at the average frame rate, though we do run across a bump in functioning for the 1% low result.

Testing with For Honor shows a iii-4% improvement in performance with SMT disabled and that was really plenty to push the 3900X alee of the 9900K in this title. Of course, nosotros didn't examination the 9900K with Hyper-Threading disabled and there's a very good risk that will boost the Intel processors performance in this championship also.

Projection Cars two sees a small 2-four% comeback in performance with SMT disabled, and while that's prissy to see, the 9900K is in no danger of losing the performance crown in this title.

Functioning when testing with Full War 3 Kingdoms is virtually identical, we come across a ane-2 fps advantage in favor of the SMT disabled configuration, merely that's pretty well within the margin or error.

PlayerUnknown's Battlegrounds sees no more than than a i% change in operation with SMT disabled so cypher to encounter hither.

We encounter a very small performance regression when testing with The Witcher three though once again, just a ane-two fps difference is within the margin or fault. And then information technology's off-white to say functioning goes unchanged in this title.

Forza Horizon iv is a mostly GPU leap game but however we see a very small performance regression with SMT disabled. Reducing performance by 3% isn't a large deal, though it certainly doesn't assistance the 3900X close in on the 9900K.

F1 2019 sees a modest performance improvement with SMT disabled.

Performance in Far Cry New Dawn went virtually untouched, at least we run into the same 112 fps on average. However as we found often the ane% low performance did take a hit with SMT disabled, we're just talking most a ~3% functioning drop, but that'southward non what we want to see.

Testing with Strange Brigade shows less than a ane% change to the boilerplate frame charge per unit, though nosotros practice see a 5% reduction for the i% depression figure. So you'll want to leave SMT enabled for this title.

Interestingly the boilerplate frame charge per unit was virtually the aforementioned with SMT disabled in Battleground Five, we come across quite a substantial reduction in performance for the ane% low issue as frame rates dropped past 14%. So this looks to be another title were you lot really don't want to disable SMT.

Moving on to Assassin'due south Creed Odyssey and nosotros tested this game more than a few times simply to make sure there was a regression. We saw a 7% drop for the average frame rate and a nine% drop for the 1% depression.

Disabling SMT does assist with performance in World of Tanks, hither the 3900X enjoyed a iii% heave to the average frame rate and now the 9900K is just v% faster, though it's possible disabling Hyper-Threading volition besides improve performance for the 9900K.

Fortnite is the kind of game nosotros'd await or approximate disabling SMT could assistance with and that looks to exist the case, sort of. Frankly, results are well within the margin or fault...

Hitman 2 is always an interesting championship that stands out for ane reason or another. Here we see a rather large ten% improvement for the average frame rate and now the 3900X is just behind the 9900K, though the 1% low functioning is improved by a mere 2%.

Functioning in Resident Evil two goes virtually unchanged.

Performance in The Sectionalisation ii was pretty much identical with out without SMT support, at least when looking at the boilerplate frame rate. We come across a 6% reduction with SMT disabled for the one% low frame rate. While testing this game without SMT we likewise noticed that the one% low result tended to fluctuate quite a bit and that is something we didn't see with 24 threads active.

Last upwards is the Shadow of the Tomb Raider and here we run into a nice seven% improvement for the boilerplate frame charge per unit, simply as nosotros've seen a number of times now, the 1% low functioning takes a small hit.

Putting 36 Game Results Together

Disabling SMT certainly looks to be a mixed bag, and we tried to go title by championship but we have results for even more games that we tested, starting with the boilerplate frame rate results.

On average the Ryzen 9 3900X was just 1% slower overall with SMT enabled, its standard out of the box configuration when yous get all the 24 threads with simultaneous multithreading enabled. Here we see that the performance margin is inside 5% for the vast majority of the titles tested, and we would fence that we saw a negligible operation deviation in 31 of the 36 games tested.

Leaving SMT enabled only improved performance in Assassin'south Creed Odyssey while disabling information technology saw some gains in Shadow of the Tomb Raider, But Crusade 4, Prey and Hitman 2.

All the same every bit nosotros observed when looking at games individually, the average frame charge per unit doesn't tell the whole story.

Let'due south too come across how 1% low figures stack up...

Comparing 1% low operation sees the results swing dorsum in SMT's favor.

Leaving SMT enabled provided a 1% performance uplift on average across the 36 games tested. This ways we encounter a 5% of better operation improvement in viii games, with a 5% or larger operation drop in just 4 games.

Just as nosotros plant two years ago when testing the Ryzen 7 1800X, disabling SMT tin exist of some do good but your mileage will vary and depend strictly on the game (workload) and is just every bit likely to crusade a regression in performance.

What disabling SMT doesn't practise is allow the Ryzen 9 3900X to shell the Core i9-9900K in games or even catch upwards to information technology. But so once more nosotros don't really demand something to justify the purchase, the 3900X and all other tertiary-gen Ryzen chips do what they do well and if you're later on a solid all-rounder the Ryzen nine processor is it.

As we've seen already, the 3900X is plenty enough for high-end gaming and where it lacks a few frames it makes up for with significantly improved productivity performance and the ability to tackle more than tasks simultaneously. It also runs much cooler, consumes a little less power, and works fine with the provided stock libation.

We don't recommend you disable SMT, unless you know that doing so will improve the performance in the specific game you'll exist playing. We're not sure why turning SMT off hurts one% low functioning in and so many games. At first we thought maybe it was because you lot go from a situation where the active threads required by the game can be utilized in a unmarried core complex die with SMT enabled, to a situation where those threads are spread beyond both CCD'due south with SMT disabled. Nevertheless, that doesn't seem to make sense given the 3900X more often than not offers ameliorate gaming performance than the 3700X, and we believe that's considering information technology has two CCD'due south which increases the L3 cache capacity too every bit the write lanes to the IO Die. Nosotros've reached out to AMD for their take on this, and so if we hear anything interesting we'll study back with a footnote here.

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