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Max RAM Speed Limited by Processor?

EmperorK
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Hi, (I have tried searching for this but couldn't find anything concrete).

 

According the Intel, under 'Memory Types' I see DDR4-2933 here: https://ark.intel.com/content/www/us/en/ark/products/186605/intel-core-i9-9900k-processor-16m-cache-up-to-5-00-ghz.html

 

Is this an indication of maximum RAM speed? I'm guessing likely not given the amount of discussion on overclocking. If not, what is this figure actually implying?

 

In my mind, RAM speed was pretty much limited by mobos and of course to a degree, PSU, OC limits and stability. I hadn't noticed RAM speed limitations by processor before.....

 

Thanks in advance!

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It's talking about max memory speed without overclocking, so you're correct

CPU: i7-2600K 4751MHz 1.44V (software) --> 1.47V at the back of the socket Motherboard: Asrock Z77 Extreme4 (BCLK: 103.3MHz) CPU Cooler: Noctua NH-D15 RAM: Adata XPG 2x8GB DDR3 (XMP: 2133MHz 10-11-11-30 CR2, custom: 2203MHz 10-11-10-26 CR1 tRFC:230 tREFI:14000) GPU: Asus GTX 1070 Dual (Super Jetstream vbios, +70(2025-2088MHz)/+400(8.8Gbps)) SSD: Samsung 840 Pro 256GB (main boot drive), Transcend SSD370 128GB PSU: Seasonic X-660 80+ Gold Case: Antec P110 Silent, 5 intakes 1 exhaust Monitor: AOC G2460PF 1080p 144Hz (150Hz max w/ DP, 121Hz max w/ HDMI) TN panel Keyboard: Logitech G610 Orion (Cherry MX Blue) with SteelSeries Apex M260 keycaps Mouse: BenQ Zowie FK1

 

Model: HP Omen 17 17-an110ca CPU: i7-8750H (0.125V core & cache, 50mV SA undervolt) GPU: GTX 1060 6GB Mobile (+80/+450, 1650MHz~1750MHz 0.78V~0.85V) RAM: 8+8GB DDR4-2400 18-17-17-39 2T Storage: HP EX920 1TB PCIe x4 M.2 SSD + Crucial MX500 1TB 2.5" SATA SSD, 128GB Toshiba PCIe x2 M.2 SSD (KBG30ZMV128G) gone cooking externally, 1TB Seagate 7200RPM 2.5" HDD (ST1000LM049-2GH172) left outside Monitor: 1080p 126Hz IPS G-sync

 

Desktop benching:

Cinebench R15 Single thread:168 Multi-thread: 833 

SuperPi (v1.5 from Techpowerup, PI value output) 16K: 0.100s 1M: 8.255s 32M: 7m 45.93s

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1 minute ago, Jurrunio said:

It's talking about max memory speed without overclocking, so you're correct

Thank you for such a fast response!

 

Given that the CPU doesn't 'know' it's being overclocked as such, are you saying you need to OC the CPU just to support say 3600 RAM, or is OCing the RAM sufficient?

If OCing the RAM is sufficient, i.e. no real interaction with the CPU in this isolated example, I'm not understanding why limitations are quoted at all for CPUs if OCing the RAM 'does the job'.

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1 minute ago, EmperorK said:

Thank you for such a fast response!

 

Given that the CPU doesn't 'know' it's being overclocked as such, are you saying you need to OC the CPU just to support say 3600 RAM, or is OCing the RAM sufficient?

If OCing the RAM is sufficient, i.e. no real interaction with the CPU in this isolated example, I'm not understanding why limitations are quoted at all for CPUs if OCing the RAM 'does the job'.

There is such thing called a memory controller, which is embedded into the CPU

CPU: i7-2600K 4751MHz 1.44V (software) --> 1.47V at the back of the socket Motherboard: Asrock Z77 Extreme4 (BCLK: 103.3MHz) CPU Cooler: Noctua NH-D15 RAM: Adata XPG 2x8GB DDR3 (XMP: 2133MHz 10-11-11-30 CR2, custom: 2203MHz 10-11-10-26 CR1 tRFC:230 tREFI:14000) GPU: Asus GTX 1070 Dual (Super Jetstream vbios, +70(2025-2088MHz)/+400(8.8Gbps)) SSD: Samsung 840 Pro 256GB (main boot drive), Transcend SSD370 128GB PSU: Seasonic X-660 80+ Gold Case: Antec P110 Silent, 5 intakes 1 exhaust Monitor: AOC G2460PF 1080p 144Hz (150Hz max w/ DP, 121Hz max w/ HDMI) TN panel Keyboard: Logitech G610 Orion (Cherry MX Blue) with SteelSeries Apex M260 keycaps Mouse: BenQ Zowie FK1

 

Model: HP Omen 17 17-an110ca CPU: i7-8750H (0.125V core & cache, 50mV SA undervolt) GPU: GTX 1060 6GB Mobile (+80/+450, 1650MHz~1750MHz 0.78V~0.85V) RAM: 8+8GB DDR4-2400 18-17-17-39 2T Storage: HP EX920 1TB PCIe x4 M.2 SSD + Crucial MX500 1TB 2.5" SATA SSD, 128GB Toshiba PCIe x2 M.2 SSD (KBG30ZMV128G) gone cooking externally, 1TB Seagate 7200RPM 2.5" HDD (ST1000LM049-2GH172) left outside Monitor: 1080p 126Hz IPS G-sync

 

Desktop benching:

Cinebench R15 Single thread:168 Multi-thread: 833 

SuperPi (v1.5 from Techpowerup, PI value output) 16K: 0.100s 1M: 8.255s 32M: 7m 45.93s

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Aha... let me see if I have this right.

 

The BIOS reads the memory controller on the CPU and sees a figure of say 2666. The BIOS then by default limits memory speed to 2666. The RAM is rated at 3600. BIOS by default then limits this RAM to 2666 as this is what the memory controller is telling the BIOS.

 

Then, you OC the RAM up to 3600. This action overrides the speed cap (which has been set by the BIOS rather than the CPU, but as a result of reading from the memory controller on the CPU) and allows the RAM to run at 3600. No interaction has directly taken place with the CPU here, the RAM is OCed and will run as such in a standard windows 10 build.

 

Is that the right way of thinking about it?

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