B660 Tomahawk Non-K cpu

[cicadanight8159102e1]

Just bought a b660 tomahawk ddr5 board. When i check the motherboard from msi's site to decide which ram to buy (compatibility), i saw a warning message there: The support of XMP speed might be limited when Non-K CPU was adopted.
İ have few questions:
- Can you overclock ddr5 ram on b660 motherboard(it says 6200mhz in motherboard's specs). or do i need z690 for that?
- İf i can overlock, do i need K cpu??
İ am planning to use this board with i7 12700 non-K. Motherboard specs says it supports up to 6200mhz ram.

Any chance that i will have issue about XMP in such a system?
B660 Tomahawk Wifi DDR5
i7 12700f
DDR5 6000mhz CL36 or similiar ram compatible with the motherboard.

Or i may be unable to use the ram's full potential just because i have non K 12700? Confused about that.

 

[citay]

Yes, you will most likely have an issue with a non-K CPU when using RAM with a high-speed XMP profile. The problem is that an important IMC (integrated memory controller)-related voltage is fixed to a low value with a non-K CPU. See here: https://forum-en.msi.com/index.php?threads/msi-forum-moderator-tool-space-–-bios-software.374208/#post-2118771

Basically, with Alder Lake 12th gen CPUs, they have an integrated voltage regulator for some parts of the CPU. Unlike with 11th gen CPUs, where the mainboard supplies all the different voltages that the different parts of the CPU requires, with 12th gen some of those voltages are transformed in the CPU itself, from a main voltage that the mainboard delivers. But with a non-K CPU, the "CPU SA" (System Agent) voltage is fixed. The mainboard can do nothing about it, since it only delivers the main voltage.

With the SA voltage fixed at a low value, the memory controller becomes quite limited. It needs more voltage for stability at higher frequencies. That's where you get problems with those RAM kits that have a pretty fast XMP profile. You can also forget about RAM overclocking. Yes, Intel allows RAM overclocking on B660 now, but the limit is the IMC (which is voltage-limited), not the RAM itself.

Overall, i would question the need for a DDR5 board + DDR5 RAM. In general, from a cost/performance standpoint, it's not very good. With DDR5, the problem is the much higher price for the modules, and the fact that the "real" modules are starting at 16 GB size, so you will always have 32 GB total RAM in the end even if you don't need that much. Overall this will be a much higher price than getting a DDR4 board and DDR4 RAM. Add to that the problems you can expect with a non-K CPU, which limits you to lowly DDR5 speeds, and a DDR4 setup becomes even more attractive than it already is. If you need 32 GB total, get 2x 16 GB DDR4-3200 with nice timings.

Why DDR4-3200 and not -3600? Well, you still have the same problem with a non-K CPU for DDR4, meaning a fixed VCCSA, which may not manage DDR4-3600 in Gear1 mode (Gear1 is important for performance). But DDR4-3200 with nice timings won't limit you too much, and it's dirt cheap. Actually, from the price savings of choosing DDR4 over DDR5, you could probably get a 12700K, which can then be paired with DDR4-3600 with nice timings. And such DDR4-3600 has much lower latencies than most DDR5 RAM. It will at least be on a level with DDR5-5200, in games the DDR4 is even faster (games really like low latencies over bandwidth).

 

[cicadanight8159102e1]

Thanks very. Those were excatly what i wanted to know.
So i should send b660 board back, or use it with K cpu which does not make much sense on a b660 board.
What you say about getting ddr4 and using that saved money for 12700k does makes sense. But wouldn't a ddr4 3600 limit the potential of such a powerful cpu 12700k, compared to a DDR5 ram such as 6000mhz cl36? İ know difference is small but even a small difference is difference if i can't use the full potential of the high end processor i bought for much higher price.
Anyway i got what i wanted. İ will decide based on what you explained here . Thanks.

 

[citay]

No, DDR4-3600 with decent timings will not really limit the 12700K.

Here you see the scaling for application performance: https://www.techpowerup.com/review/ddr5-memory-performance-scaling/2.html
DDR4-3600 is within 4% of DDR5-6000 CL36.

And here with gaming performance in WQHD: https://www.techpowerup.com/review/ddr5-memory-performance-scaling/5.html
DDR4-3600 is within less than 1% of DDR5-6000 CL36.

Since a non-K CPU might have to make do with a low DDR5 speed (for example DDR5-4800), you will have worse or equal performance compared to DDR4-3600, but higher price still.

So either you go "all out" now, disregarding the cost, which would mean 12700K on your DDR5 board, together with DDR5-6000 CL36. This will cost you a pretty penny, but you remove even the last 4% of limitation you might have had from the RAM. Or you come up with a solution that has better price/performance.

 

[cicadanight8159102e1]

Going price performance seems better choice of course. İt is nonsense to spend that much for high end ram and high end cpu but not for motherboard and use that b660. Either way i have to send it back. Get a ddr5 z690 or ddr4 b660. Thanks.

 

[joe c]

Yes, you will most likely have an issue with a non-K CPU when using RAM with a high-speed XMP profile. The problem is that an important IMC (integrated memory controller)-related voltage is fixed to a low value with a non-K CPU. See here: https://forum-en.msi.com/index.php?threads/msi-forum-moderator-tool-space-–-bios-software.374208/#post-2118771

Basically, with Alder Lake 12th gen CPUs, they have an integrated voltage regulator for some parts of the CPU. Unlike with 11th gen CPUs, where the mainboard supplies all the different voltages that the different parts of the CPU requires, with 12th gen some of those voltages are transformed in the CPU itself, from a main voltage that the mainboard delivers. But with a non-K CPU, the "CPU SA" (System Agent) voltage is fixed. The mainboard can do nothing about it, since it only delivers the main voltage.

With the SA voltage fixed at a low value, the memory controller becomes quite limited. It needs more voltage for stability at higher frequencies. That's where you get problems with those RAM kits that have a pretty fast XMP profile. You can also forget about RAM overclocking. Yes, Intel allows RAM overclocking on B660 now, but the limit is the IMC (which is voltage-limited), not the RAM itself.

Can B660 Tomahawk + non-K CPU use XMP profile for DDR4 RAM?

 

[citay]

Can B660 Tomahawk + non-K CPU use XMP profile for DDR4 RAM?

Yes, but the problem is what DDR4 speed the XMP profile is. You might be getting problems when trying to pass memory training at DDR4-3600 Gear1 mode, simply because the fixed SA Voltage may not be high enough to achieve stability. So with DDR4-3600 XMP and definitely with even faster profiles, you could be forced to use Gear2 mode, which will cost performance. Then it's better to lower the RAM frequency enough to be able to stay in Gear1 mode.

I have to stay pretty vague here because it will also depend on the quality of your CPU's IMC (memory controller). Just like with the CPU's actual cores, some specimen achieve higher frequencies at lower voltages, while others need more voltage for the same or lower frequencies. So it's not a clear-cut thing of "works up to DDR4-xxxx". Depending on your modules, and especially when using four modules, you might already getting problems achieving DDR4-3200 Gear1 with a non-K CPU. And Gear1 is important for performance (see my RAM thread).

 

[cicadanight8159102e1]

Here an overclock to ddr5 6400 with vccsa 0.95. İt's with k processor. But can we say it is possible to do the same for any DDR5 even with non-k cpu? İs DDR5 easier to oc compared to DDR4, assuming both havenon-K cpu's. Ofc it's hard to say without testing, but if you have just an opinion i would like to know.

 

[citay]

This goes back to what i mentioned here:

I have to stay pretty vague here because it will also depend on the quality of your CPU's IMC (memory controller). Just like with the CPU's actual cores, some specimen achieve higher frequencies at lower voltages, while others need more voltage for the same or lower frequencies.

That 12900KF of his is most likely not representative of IMC quality of any non-K CPU you might get. You can never assume that you get the same results as someone else at the same voltages, for any kind of settings, because no two CPUs are the same. This goes for both CPU OC and for RAM OC, especially when the latter is potentially IMC-limited. So that's why i would be careful of drawing any general conclusions from seeing his overclock.