AMD 3D V-Cache CPU

For an astonishingly long time, the best gaming CPU you could buy was an AMD 5800X3D. Not the more powerful 5900X, or the competitor from Intel, but a special edition of the 5800X with 3D V-Cache.

In a nutshell, the reason why is down to the CPU's cache - that's a small unit of memory physically located close to the CPU that can be read quickly - which matters a lot for how fast it can work with, say, a game. Usually there's not enough space in a cache as the CPU is a thin square where the area is quite limited. AMD however, figured out that instead of extending the cache to the side, you can do it vertically, hence the 3D designation. So basically, it meant you could throw three times as much cache onto a CPU as normal, and several media outlets have called it the biggest technological innovation of the decade. It should be said, though, that it's not just something used for gaming, servers and workstations can benefit from it too.

Everyone had therefore been looking forward to it coming with AMD's Ryzen 7000 series, especially since the 5800X and 5800X3D chips didn't get a replacement, there were just a 7700X and a 7900X, but that magic middle ground wasn't there at launch - but it is now. There are currently three options, a 7950X3D, a 7900X3D and then the long awaited 7800X3D, which doesn't look likely to hit stores until early April. It should be at least $150 cheaper than the 7900X3D, though.

The price of the new 3D V-Cache editions is somewhat higher than the regular editions, clocking in at:

• AMD Ryzen 9 7950X3D: €809


• AMD Ryzen 9 7900X3D: €689

We got to take a look at the top model, the AMD Ryzen 9 7950X3D. However, there is also a 3D version of the 7900X chip, which will probably make the most sense to many as 16 cores and 32 threads is actually a lot more than you need, and AMD's boost technology very simplistically just raises the speed of the processor until you hit some heat limits.

But with the 3D V-Cache edition we not only get 144MB of cache to make do with - and that's an awful lot, but also a big reduction in power consumption, from 170 Watts to 120 Watts, but with the same if not better performance, and thus better options for overclocking, or just keeping the chip running cooler in general, which I myself am a big fan of. Graphics cards and processors are damn expensive, but if you can accept that they just run standard instead of you having to pull tons of extra watts through them for 2% more performance, well then the system is often both stable and can last for many years.

The system is such that the processor chip itself contains both normal CCX, and one with 3D V-Cache. A CCX is a unit called Core Complex that contains four CPU cores and their shared cache, the more CCX units, the more cores. Normally there is 16MB per CCX, but here there is something more to hit the 144MB. The point is that common tasks can be run normally and where high frequency is important, while the 3D V-Cache units have extremely low latency due to really high cache. This means you can keep production costs down and have a system that is flexible and scalable. Although it sounds enormously complex and automated, you can actually decide for yourself, perhaps not what I would recommend as the system analyses in real time which core should do what, but you have the option.

AMD has gone so far as to have a separate system that can automatically throw games onto the best performing CCX device, which is often the one with the most cache.

As many AMD users know, through the Ryzen Master software you can play around with your CPU and corresponding performance quite a bit. There are a number of different options, and one of the options you have is the "Curve optimizer" - it takes some time to optimise, but it can pay off. Combine that with Eco mode, where the CPU is limited in how much power it can draw, and you're still approaching 7-8% of what can be achieved at full power. Similarly, through Precision Boost Overdrive you can do one-click overclocking. It's not like you get 15-20% more, the system already pushes the cores as much as it can by itself, but there's just a few percent to be gained for those who want it.

We tested on, not surprisingly, an AM5 motherboard with DDR5 6000Mhz RAM, an NVMe 4.0 drive and an RTX 4080 card. The reason is that we're not 100% sure if AMD's Smart Access Memory works even better with the 3D editions or "just" the same way as the regular X editions, thus introducing an extra variable. The numbers should therefore not be taken as absolute, had we paired it with one of the super-tuned RX 7900 XTX cards we also borrowed, but they do give us a solid basis for comparison vs. 7950X with as few variables as possible.

We had no trouble getting above 5.7Ghz on half the cores, which makes perfect sense since those are the ones without 3D cache, and perhaps more importantly, the temperature was low, as in, below 74 degrees throughout, where with the regular 7950X chip it has often crept above 90 degrees under heavy load. Power consumption isn't too shabby either, we measured 121.99 watts at peak when not fiddling with things - but I wonder if there's more performance to be had if you set consumption free? So overall, it's in 1080p and 1440p that you see the biggest changes, simply because the GPU is typically the bottleneck in 4K gaming.

Overall, we saw improvements of 10-12% in 1080p, and 7-10% in 1440p. A few games can utilise this cache significantly better than others, Far Cry 6 delivered 48% improvement in 1080p and 49.51% improvement in 1440p - for comparison the improvement in 4K was only 4.2%.

It costs extra, but there's also a measurable improvement, which is then compensated through lower power consumption. Unfortunately, we haven't had time to play with the overclocking, but due to how there should be an extra 50 watts to play with, and therefore a huge potential to get even more performance. If you already have a 7950X, for example, it doesn't make much sense to upgrade, especially if you're into 4K resolution. But an extra 12% performance without a generational shift is worth it, even if it costs extra.