{"slug": "5090-prices-are-crazy-and-prebuilts-are-cheaper", "title": "5090 prices are crazy, and prebuilts are cheaper?", "summary": "A forum discussion of GPU pricing notes that used 8-channel memory CPUs such as AMD Epyc can deliver 110 GB/s to 128 GB/s of RAM bandwidth single-socket, with dual-socket Rome systems reported above 205 GB/s, while the CPUs themselves sell for $20-$50 and the motherboards cost $800+ for an AsRock Rack EPYC8D and $1,000 for a Gen4 ROME8D. The poster argues memory bandwidth, not core speed, is what LLM inference depends on, but adds the point is moot for image and video generation because no one encodes those workloads on CPU.", "body_md": "It’s not the single core performance. It’s the RAM channels. Those C602/C612 chipsets are all quad channel and max out at 2133/2666Mhz respectfully (I overclocked some to 2933 in V4).\n\nNah the real specs you are looking for are 8-channel memory CPUs, or higher. Think Epyc (even the original Epyc is 8-channels, and can run 2933 Mhz). I measured 110 GB/s ram with an 7551, and a Rome CPU in the same Mobo and ram clocked in at 128 GB/s. That was single socket - dual socket Rome I’ve seen people post 205+ GB/s memory bandwidth on reddit.\n\nCPUs are dirt cheap ($20-$50). But it’s the Mobo that will break the bank. Even the old original AsRock Rack EPYC8D (7 x 16lanes of Gen3) commands $800+ on ebay. ROME8D that is Gen4, $1000.\n\nThat’s all LLM inference cares about, memory speed not core speed.\n\nHowever, the OP is asking about image and video generation. So the point is mute because no one encodes on CPU for those.", "url": "https://wpnews.pro/news/5090-prices-are-crazy-and-prebuilts-are-cheaper", "canonical_source": "https://forum.level1techs.com/t/5090-prices-are-crazy-and-prebuilts-are-cheaper/256321#post_6", "published_at": "2026-09-17 20:22:40+00:00", "updated_at": "2026-09-17 20:23:52.739081+00:00", "lang": "en", "topics": ["ai-infrastructure", "large-language-models"], "entities": ["AMD", "Epyc", "AsRock Rack EPYC8D", "ROME8D", "Epyc 7551", "Rome"], "alternates": {"html": "https://wpnews.pro/news/5090-prices-are-crazy-and-prebuilts-are-cheaper", "markdown": "https://wpnews.pro/news/5090-prices-are-crazy-and-prebuilts-are-cheaper.md", "text": "https://wpnews.pro/news/5090-prices-are-crazy-and-prebuilts-are-cheaper.txt", "jsonld": "https://wpnews.pro/news/5090-prices-are-crazy-and-prebuilts-are-cheaper.jsonld"}}