DiRT Rally: Encoding Performance of i5-8400 vs. R5 1500X (Faster)
Although we recently added DOTA and have done some work with CSGO, DiRT Rally remains our go-to for stream tests. It’s not that a lot of people are streaming it, just that the game is easy to work with and provides us with a trustworthy baseline.
At 1080p60, ultra settings and advanced blending, and a 1080p60 output to YouTube stream with a 10Mbps bit-rate, we get the results shown now. The i5-8400 stock CPU only delivers about 31% of its frames, showing that this workload is too difficult for the 6-core, and the R5 1500X only delivers 7.7% of its frames. We have to drop from the Faster H264 profile to better accommodate these low-end CPUs, as our testing thus far has only dealt with i7s, R7s, and X299 or X399 CPUs.
Anyway, because this is clearly not usable as a streamed output, let’s just look at it as a synthetic test for the starter. Even with these dismally low encoded frame counts of 31% on the 8400 and 7.7% on the 1500X, which means we’re dropping 69% and 92% of frames, respectively, we can still look at the frame delivery latencies. The R5 1500X manages to deliver 73% of its very low count of frames within the 16.7ms ideal window, with the 8400 delivering 56% of its frames in that same 16.7ms window. We can’t make much of this just yet, as the 8400 is clearly delivering significantly more frames than the 1500X, though both are completely unusable for this configuration.
Out of desperation, and before dropping quality, we switched to high priority for OBS. This previously worked to help save the i7-7700K from general uselessness in a similar test, so it might help here. We do end up delivering 100% of frames from the i5-8400 when switching OBS to high priority, but there’s a hit to player-side performance; we’ll look at that momentarily, after this chart. The 1500X manages now to deliver 61% of its frames, dropping about 38.7%, and is also improved. We can also see that, again, the 1500X manages to deliver more in the +/-2% window of 16.7ms, but it’s dropping so many that it’s still a poor match for this streaming configuration. It’s too much of a workload.
The player-side FPS chart will help better reveal whether the higher priority OBS workload murders the ability to play and enjoy the game, though. As we talked about in our R7 1700 & i7-7700K benchmarks previously, it’s possible to deliver 100% of frames and still have an awful experience. If you’re only able to render, for example, 30FPS on the player-side, then you obviously have a lot fewer frames available to encode to stream than with a 60+FPS render output.
DiRT Rally: Streamer-Side Performance (10Mbps, Faster)
As a refresher, these FPS charts consist of streamer-side FPS, and make up the other half of the equation. There are two FPS numbers per CPU, minimum: Baseline, which establishes performance when playing without a stream, and streamed output. The delta between the two tells us how much loss there is in performance when streaming.
Baseline FPS, the i5-8400 manages 109FPS AVG, 86FPS 1% lows, and 78FPS 0.1% lows. We are right up against the limits. The R5 1500X performs effectively the same with this video card and with these settings, making the two roughly tied pre-stream. Note that the 8400 and 1500X are not tied in gaming benchmarks, but this test is quite a bit different than those; we’ll publish the full review and gaming benchmarks shortly hereafter.
In the meantime, though, they’re equal pre-stream. During the stream, the i5-8400 outputs 107FPS AVG, 81FPS 1% lows, and 34FPS 0.1% lows. It has lost effectively 0% of its performance, but it is also failing to output any frames to stream. If you remember correctly from the previous chart, the 8400 was only successfully encoding 31% of frames, with the 1500X only encoding 8% of frames.
The 8400 gives the streamer a great experience, but the viewers get an unwatchable experience. The R5 1500X drops more of its frames, falling to 97FPS AVG, but is still spending more resources than necessary on streamer gameplay, and not enough resources on the OBS encoding.
Changing to High Priority for each CPU means we lose in streamer-side FPS, but improve encoded frame output. The i5-8400 is not giving the player 51FPS AVG, with lows somewhat dismal at 11FPS 1% and 7FPS 0.1%. This is effectively unplayable, but we do manage to deliver 100% of frames. To be fair, there aren’t many to deliver, at this point, and it’s still not usable. The R5 1500X with High Priority does even worse, at 33FPS AVG and with 61% frames delivered.
Just to reiterate: This test has traditionally been a mainstay for us, in our limited time with these new streaming benchmarks, and has been adequate for most testing. With these two CPUs, it’s just too much work. We’ll need to drop down to something easier for mid-range CPUs, like encoding with Superfast instead of Faster.
For this particular game, superfast doesn’t drop our visual quality in a noticeable way; at least, not by the time it gets to YouTube, Superfast and Faster both appear similar enough to not be worth the obvious performance hit on cheaper CPUs. The fact that Superfast allows us to output an actual stream, rather than a choppy slideshow, also outweighs any minor quality difference. This is where the R7 and 8700K CPUs come into play: They’re able to sustain slower encoding rates with better throughput.
DiRT Rally: Superfast H264 Streaming (i5-8400 & R5 1500X)
Here’s the chart. With all the same settings except for the H264 encode mode, which is now Superfast, we’re able to encode 100% of frames at 60FPS to the YouTube stream. The R5 1500X and i5-8400 drop 0% of frames each. Looking at the frame latencies, we see that the R5 1500X encodes 53.85% of its frames within the ideal 16.7ms window – which is a 60FPS refresh, if you were to divide 1000ms by 60 frames per second – with 17.7% delivering faster than 16.7ms and 28.5% delivering slower. Being faster is value-less, here; you really just want consistency, sort of like VR gaming.
As for the i5-8400, 51.3% of its frames are encoded within the 16.7ms window, with 21.2% outputting faster than that window and 27.5% outputting slower. Both CPUs do manage to achieve a 100% frame encode marker, to their credit, but they also achieve that mark chaotically. There is minimal precision between each. The 51.3% versus 53.9% numbers are also close enough to be effectively equal, especially since we don’t run as many stream passes as with the shorter game tests.
The good news is that we are actually able to stream this game successfully, just with a lower quality output. Let’s take a look at streamer-side FPS and experience.
DiRT Rally: Superfast H264 FPS Streamer Experience
The baseline performance remains the same as previously, of course, so we’re looking at numbers of roughly 109FPS AVG for each CPU, against the limits. The R5 1500X drops to 99FPS AVG, 72FPS 1% low, and 29FPS 0.1% lows. The 4C/8T R5 CPU is therefore dropping about 10% in streamer-side performance in order to maintain a fluid output stream, but we’re still well within playable territory.
The i5-8400, meanwhile, manages to keep nearly all of its original performance, because the superfast encoding and gameplay aren’t generating enough work to fully engage and trip-up the CPU, as the previous test did. It’s still a heavy workload, but it’s not nearly as heavy. The low framerates are around where the 1500X is, with a 0.1% frame latency converting to 32FPS. This fits the profile we’ve created for all CPUs when streaming on the host system: We lose consistency in low-end frame latencies by initiating a stream, which means ultra-competitive players in games like CSGO or DOTA2 may be more sensitive to the loss. Using an external capture system would remove this concern but, subjectively speaking, we don’t notice the difference too often with this game.
When dropping to Superfast from Faster, both CPUs are able to keep up with both the encoding workload and gaming workload. The Ryzen CPU drops about 10% of its baseline FPS to accommodate the stream, while the Intel CPU manages to hang on and is capped elsewhere – we’ll explore this in the DOTA test. Neither is outright superior to the other in streaming output.
Let’s move to DOTA2.
DOTA2 Streaming & Gaming at 10Mbps, Faster (i5-8400 vs. R5 1500X)
Using the same unplayable settings that we used for DiRT Rally, capturing DOTA2 at 10Mbps with a 1080p60 output and Faster preset made the stream completely unwatchable. Dropped about 98% of frames on both the i5-8400 and R5 1500X, leaving us with fewer than 3% of frames encoded to the stream. Switching to high priority resolved this for each CPU, giving us a full 100% encoding rate, but lower frames in-game.
This is revealed when looking at the FPS chart. The stock 8400 and stock 1500X both have significantly higher framerates when no process is given priority, but the stream is useless, so they have functionally failed the test. The 8400 has a baseline performance ceiling of 163FPS AVG, with 82 and 40FPS lows. The 1500X baseline is 108 AVG, with lows at 53 and 27. Moving to the high prioritization, the 8400 manages a 70FPS AVG player-side throughput, but introduces noticeable frame latency that computes to 12FPS 0.1% lows. It’s loosely playable, and the stream is great, but it’s just frustrating enough to demand better performance. You’d want to drop the encoding settings a bit.
The R5 1500X, meanwhile, just can’t keep up. At 28FPS AVG and lows sub-10FPS, it’s just not playable, despite the stream encoding all frames. To be fair, of course, there aren’t many frames to encode.
Moving to Superfast should be more realistic.
DOTA2 Superfast: i5-8400 vs. R5 1500X
Streaming with Superfast encoding, we’re able to output 100% of the frames from both the i5-8400 and R5 1500X, making them functionally equivalent as far as the stream viewer is concerned. That said, the R5 1500X does manage one noteworthy feat: Of its frames delivered, the CPU keeps 94.6% of them within +/-2% of 16.7ms, whereas the i5-8400 is closer to 65%. This follows previous trends, though they were less noticeable. We don’t yet have enough data to fully draw conclusions, but it may be that, when the Ryzen CPU is under less duress and strain for frequency, its additional threads are assisting in frame pacing.
Looking at FPS, the i5-8400 delivers a decisive victory, here, managing a 59% lead over the R5 1500X streaming test. We’re at 135FPS AVG versus 85FPS AVG. Part of this difference contributes to the i5’s more chaotic frame pacing and, just like with the 7700K, you’d be best off doing some manual tuning on this CPU to get the most out of it. We’d recommend some tuning of affinities on the CPU threads. Ryzen still manages reasonably well at 85FPS AVG while delivering 100% of the frames to the stream, but the i5-8400 is also capable of the task, though with less precision on encoding.