The Intel 12th Gen Core i9-12900K Review: Hybrid Performance Brings Hybrid Complexity
by Dr. Ian Cutress & Andrei Frumusanu on November 4, 2021 9:00 AM ESTCPU Tests: SPEC MT Performance - DDR5 Advantage
Multi-threaded performance is where things become very interesting for Alder Lake, where the chip can now combine its 8 P-cores with its 8 E-cores. As we saw, the 8 E-cores are nothing to sneeze about, but another larger consideration for MT performance is DDR5. While in the ST results we didn’t see much change in the performance of the cores, in MT scenarios when all cores are hammering the memory, having double the memory channels as well as +50% more bandwidth is going to be extremely beneficial for Alder Lake.
As we noted, the DDR5 vs DDR4 results showcase a very large performance gap between the two memory technologies in MT scenarios. Running a total of 24 threads, 16 for the SMT-enabled P-cores, and 8 for the E-cores, Alder Lake is able to take the performance crown in quite a lot of the workloads. There are still cases where AMD’s 16-core setup with larger cores are able to perform better, undoubtedly also partly attributed to 64MB of on-chip cache.
Compared to the 11900K, the new 12900K showcases giant leaps, especially when paired with DDR5.
In the FP suite, the DDR5 advantage in some workloads is even larger, as the results scale beyond that of the pure theoretical +50% bandwidth improvement. What’s important for performance is not just the theoretical bandwidth, but the actual utilised bandwidth, and again, the doubled up memory channels of DDR5 here are seemingly contributing to extremely large increases, if the workload can take advantage of it.
In the aggregate results, there’s very clearly two conclusions, depending on whether you use the chip with DDR5 or DDR4.
With DDR4, Alder Lake and the 12900K in particular, is able to showcase very good and solid increases in performance, thanks to the IPC gains on the Golden Cove core, but most importantly, also thanks to the extra 8 Gracemont cores, which do carry their own weight. The 12900K falls behind AMD’s 5900X with DDR4, which is fair given the pricing of the chips here are generally in line with teach other.
With DDR5, the 12900K is able to fully stretch its multi-threaded performance legs. In less memory dependent workloads, the chip battles it out with AMD’s 16-core 5950X, winning some workloads, losing some others. In more memory dependent workloads, the DDR5 advantage is extremely clear, and the 12900K is able to blow past any competition, even slightly edging out the latest Apple M1 Max, released a few weeks ago, and notable for its memory bandwidth.
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Wrs - Saturday, November 6, 2021 - link
Nah, they just weren't that competitive. Athlon64 was decent (lot of credit to Jim Keller) but didn't let AMD take massive advantage of Intel's weakness during the Pentium 4 era because AMD fabs were capacity limited. Once Conroe came out mid 2006 the margins dried up rapidly and AMD had no good response and suffered a talent exodus. It's true Intel made it worse with exclusivity bonuses, but I think AMD's spiral toward selling their fabs would have happened anyway. No way they were going to catch up with tick-tock and Intel's wallet.GeoffreyA - Monday, November 8, 2021 - link
I've always felt the K10 wasn't aggressive enough, owing to AMD not having factored Conroe into their equations when K10 was designed. Then, like startled folk, they tried to take back the lead by a drastic departure in the form of Bulldozer; and that, as we know, sank them into the ditch. Nonetheless, I'm glad they went through the pain of Bulldozer: Zen wouldn't have been as good otherwise.mode_13h - Tuesday, November 9, 2021 - link
> FX series was as bad as it was for a couple of reasonsI thought I also heard they switched from full-custom layout to ASIC flow (maybe for the sake of APUs?). If so, that definitely left some performance on the table.
bunnyfubbles - Thursday, November 4, 2021 - link
3D v-cache will be out before Zen 4 and should help close the gap if not regain the overall lead on the high end. The problem for AMD is the competition below the i9 vs R9 realm, where the E cores really pull more than their weight and help the i9 compete with the R9s in multi, but for the i5s and i7s vs their R5 and R7 counterparts, its even-Steven with performance cores, then you have the E cores as the trump card.MDD1963 - Thursday, November 4, 2021 - link
If AMD gains an averge of ~10% in gaming FPS with the 3D cache onslaught, that should put them right back near the top...certainly much closer to the 12900K....geoxile - Thursday, November 4, 2021 - link
15% on average. 25% at the highest. Intel really should have offered a 16 P-core die for desktop smdh, classic intel blunderSpunjji - Friday, November 5, 2021 - link
That would be a hell of a large die and necessitate a total redesign of the on-chip fabric. I don't think it would really make any sense at all.RSAUser - Monday, November 8, 2021 - link
12900K is already huge, each performance core is the size of about 4 E cores, going 16C P-Core would probably mean a 70% die size increase, and then you run into core to core communication issues, AMD got around it with infinity fabric but that's why you have the higher latency access between cores in different core complexes and Intel gives a more consistent access time on higher end products. Intel's current cores are mosly ringbus, so travel from one core to the next, getting to 16 doesn't scale well, they used a mesh topology in some Skylake CPU's, that latency was too high and hampered performance badly, you'd run into that same issue with 16C.That's without checking into yield, getting 16C on one wafer that are all perfectly clocking high is going to be a very, very rare chip; AMD gets around it using the core complexes (CX) of 4 cores each, together into a CCD (core chiplet die) and then in Zen 3 (5000 series) is supposedly 8C CCX, which makes rare chips 8C if full ccx works well, else 6C if 2 can't make it turns into a 5600X.
StevoLincolnite - Friday, November 5, 2021 - link
AMD has an answer before Zen 4.And that is Zen 3 with V-Cache.
Spunjji - Friday, November 5, 2021 - link
"This is their Zen 1 moment"Indeed!
"at a lower price"
Not really, if you take platform into account (and you have to!)
"Zen 4 isnt even competing with Alder Lake, Raptor Lake is rumored to be out before Zen 4"
Potentially, but Zen 4 is a bigger jump from Zen 3 than Raptor is predicted to be from Alder. Raptor will have more E cores but it's on the same process, so it's likely to offer better perf/watt in multithreading but unlikely to increase overall performance substantially (unless they allow maximum power draw to increase).
"AMD has really screwed up with their launch cycle"
Not really? They're still competitive in both price/performance (accounting for platform cost) and perf/watt. Zen 3D should shore up that position well enough.
"Intel is truly back"
Yup!