Please help me understand RAM limitations for this build (Ryzen 7800X3D, B650)

Posted by smittyplusplus@reddit | buildapc | View on Reddit | 11 comments

Hi all, I posted recently and bought parts for this pc build, final part list is below. However, I couldn't get the board to post with all 4 RAM sticks installed. When I put 1x32GB in slow DDR5\_A2 and 1x32GB in DDR5\_B2, It will boot. In this 2x32GB configuration, the BIOS shows G.SKILL 32GB 4800MT/s, even though the RAM is 6000, and the [board is allegedly up to 256GB with a lot of different speeds up to 8000(OC)](https://www.gigabyte.com/Motherboard/B650-AORUS-ELITE-AX-rev-12/sp#sp). I have since found a couple of things I don't understand entirely: * [other reddit posts](https://www.reddit.com/r/gigabyte/comments/1artb83/comment/kr6jntr/?utm_source=share&utm_medium=web3x&utm_name=web3xcss&utm_term=1&utm_content=share_button) suggesting strange rules for AMD processors and RAM speeds, etc. * the board's support page has [a memory support tool that shows](https://www.gigabyte.com/Motherboard/B650-AORUS-ELITE-AX-rev-12/support#support-memsup) no supported ram that has "memory socket support" of 4 for 32GB at 6000. And this specific G-Skill ram I have shows supported for 2 slots at 6000 (yet, again, this shows in bios at 4800). Can someone help me understand, is it even possible to use 4x32GB of 6000/30CAS ram with this system? Or is this a limitation of the CPU/architecure? Or do I need a different board? Or different RAM? I'm super confused here :-P Any help would be appreciated. [PCPartPicker Part List](https://pcpartpicker.com/list/LPqw74) |Type|Item|Price| |:-|:-|:-| |**CPU**|[AMD Ryzen 7 7800X3D 4.2 GHz 8-Core Processor](https://pcpartpicker.com/product/3hyH99/amd-ryzen-7-7800x3d-42-ghz-8-core-processor-100-100000910wof)|$479.00 @ Amazon| |**CPU Cooler**|[Thermalright Peerless Assassin 120 SE 66.17 CFM CPU Cooler](https://pcpartpicker.com/product/hYxRsY/thermalright-peerless-assassin-120-se-6617-cfm-cpu-cooler-pa120-se-d3)|$34.90 @ Amazon| |**Motherboard**|[Gigabyte B650 AORUS ELITE AX ATX AM5 Motherboard](https://pcpartpicker.com/product/WBwypg/gigabyte-b650-aorus-elite-ax-atx-am5-motherboard-b650-aorus-elite-ax)|$209.99 @ Amazon| |**Memory**|[G.Skill Flare X5 64 GB (2 x 32 GB) DDR5-6000 CL30 Memory](https://pcpartpicker.com/product/6QcgXL/gskill-flare-x5-64-gb-2-x-32-gb-ddr5-6000-cl30-memory-f5-6000j3040g32gx2-fx5)|$179.99 @ Newegg| |**Memory**|[G.Skill Flare X5 64 GB (2 x 32 GB) DDR5-6000 CL30 Memory](https://pcpartpicker.com/product/6QcgXL/gskill-flare-x5-64-gb-2-x-32-gb-ddr5-6000-cl30-memory-f5-6000j3040g32gx2-fx5)|$179.99 @ Newegg| |**Storage**|[Crucial BX500 1 TB 2.5" Solid State Drive](https://pcpartpicker.com/product/LFZzK8/crucial-bx500-1-tb-25-solid-state-drive-ct1000bx500ssd1)|$58.99 @ Amazon| |**Storage**|[Samsung 980 1 TB M.2-2280 PCIe 3.0 X4 NVME Solid State Drive](https://pcpartpicker.com/product/mKBG3C/samsung-980-1-tb-m2-2280-nvme-solid-state-drive-mz-v8v1t0bam)|$84.00 @ Amazon| |**Storage**|[Samsung 980 1 TB M.2-2280 PCIe 3.0 X4 NVME Solid State Drive](https://pcpartpicker.com/product/mKBG3C/samsung-980-1-tb-m2-2280-nvme-solid-state-drive-mz-v8v1t0bam)|$84.00 @ Amazon| |**Video Card**|[Asus TUF GAMING OC GeForce RTX 4070 Ti SUPER 16 GB Video Card](https://pcpartpicker.com/product/9ksV3C/asus-tuf-gaming-oc-geforce-rtx-4070-ti-super-16-gb-video-card-tuf-rtx4070tis-o16g-gaming)|$849.00 @ Walmart| |**Case**|[Corsair 4000D Airflow ATX Mid Tower Case](https://pcpartpicker.com/product/bCYQzy/corsair-4000d-airflow-atx-mid-tower-case-cc-9011200-ww)|$84.99 @ Amazon| |**Power Supply**|[Corsair RM1000x (2021) 1000 W 80+ Gold Certified Fully Modular ATX Power Supply](https://pcpartpicker.com/product/jRvdnQ/corsair-rm1000x-2021-1000-w-80-gold-certified-fully-modular-atx-power-supply-cp-9020201-na)|$189.99 @ Amazon| |**Monitor**|[Dell S3422DWG 34.0" 3440 x 1440 144 Hz Curved Monitor](https://pcpartpicker.com/product/pvrRsY/dell-s3422dwg-340-3440x1440-144-hz-curved-monitor-210-azep)|$319.99 @ Dell Technologies| |*Prices include shipping, taxes, rebates, and discounts*||| |**Total**|**$2754.83**|| |Generated by [PCPartPicker](https://pcpartpicker.com) 2025-01-25 18:27 EST-0500|||

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11 Comments

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Protocol49@reddit

It baffles me that in the year of our lord 2025 this is still an ongoing question, and even more baffling is people with no use for that much RAM by any means insist on buying it. Do you have friends that make memory chips and want to support their efforts? You can have high capacity and low speed, or low capacity and high speed. Its that simple.

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smittyplusplus@reddit (OP)

Machine learning uses (or can use) a lot of RAM, but setting that aside. It might still be a question because it's hard to find a clear answer. Your framing here is the clearest I've seen that expressed, so... thanks. LOL I think it's mostly confusing because people like me building a new AM5 system are surprised that we need to have less, slower (relative to the current top of line) RAM than our old AM4 system. Maybe I'm missing something. This would actually be quite easy for the hardware manufacturers to articulate on their specs, probably.

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Protocol49@reddit

Ok so heres the thing, DDR5 transfers more bits per cycle so it effectively acts like it has more ranks than an equivalent DDR4 setup. If you have 2x32GB of DDR5, the strain on the board and CPU is equal to 4x32GB on DDR4. This is why its so hard to run both quantity and speed. This is also why the 24/45GB modules came about, they fit extra capacity without the same demand, they're essentially 1.5 rank sticks.

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smittyplusplus@reddit (OP)

Thanks, this makes sense. BUT is also very hard to discover before screwing it up. :-P

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Protocol49@reddit

Well, we've gotten use to plug and play with XMP settings just working, unfortunately DDR5 isn't that guy lol. It won't POST at all with 4 sticks, even on auto settings? You may have to give it a looong time to train, just bear that in mind. It might take 5-10 minutes with that much RAM.

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smittyplusplus@reddit (OP)

I might give it another try and wait it out for a bit, see if it works. But, you also sufficiently shamed me in the first comment, it was convincing haha. If I'm doing big loads I'll just do something in cloud, 64GB is probably enough. I just bought a bunch of parts assuming I wanted 128 GB so I was reluctant to just give up the RAM.

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Protocol49@reddit

That wasn't directed solely at you, this is a very common complaint where people with straight gaming machines want 128GB of RAM to play Warzone, its crazy. If you can still return the sticks, you can try a 2x48GB kit. That would get you 96GB and its way more likely you'll get the advertised speed out of it.

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smittyplusplus@reddit (OP)

Oh I was kidding, I didn't take it personally. I think I'm just going to roll with 64GB 👍

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MarxistMan13@reddit

> is it even possible to use 4x32GB of 6000/30CAS ram with this system? No. If you need >96GB of RAM on a DDR5 system, you'll be limited to 5200mhz or slower. If you don't need >96GB of RAM, you should *never* use more than 2 DIMMs. You're sacrificing significant speed to do so. > Or is this a limitation of the CPU/architecure? It's a limitation of DDR5, boards, and CPU memory controllers. All of them have certain issues that combined make it significantly challenging to run 4 modules at any sort of overclock. > the BIOS shows G.SKILL 32GB 4800MT/s, even though the RAM is 6000 Enable XMP / EXPO with 2x32GB. If you need more RAM, consider 2x48GB or you'll have to settle for lower speeds (4800-5200mhz most likely).

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smittyplusplus@reddit (OP)

Thank you, kind Marxist man.

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whomad1215@reddit

Four sticks puts more strain on the memory controller Higher speeds put more strain on the memory controller Higher capacities put more strain on the memory controller This is why no one recommends four sticks on AM5, especially not four fast sticks