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AMD's Ryzen 9 9950X3D2 Dual Edition crams 208MB of cache into a single chip

arstechnica.com

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Re: AMD's Ryzen 9 9950X3D2 Dual Edition crams 208MB of cache into a single chip

#151

Post by MrDOS »

throawayonthe wrote: post #78
magicalhippo wrote: post #25

Probably fun for those who already bought DDR5 memory... still kicking myself for not just pulling the trigger on that 128GB dual stick kit I looked at for $600 back in September. Now it's listed at $4k... Meanwhile I hope my AM4 will chug along a few more years.

oh wow you weren't joking: https://pcpartpicker.com/products/memory/#xcx=0&b=ddr5&Z=131... (cheapest at $1240 USD)

PCPartPicker are also publishing charts showing the astronomic rise in DDR5 prices over time: https://pcpartpicker.com/trends/price/memory/. Those charts don't cover any kits with 64 GB sticks, but they're a good demonstration of the general scale.

Re: AMD's Ryzen 9 9950X3D2 Dual Edition crams 208MB of cache into a single chip

#152

Post by SubiculumCode »

Oh man. I am running computations on my server that involve computing geodesic distances with the heat method. The job turns out to be a L3 cache thrasher, leaving my cpus underutilized for multi worker jobs .... 208mb instead of my 25 per socket sounds amazing

Re: AMD's Ryzen 9 9950X3D2 Dual Edition crams 208MB of cache into a single chip

#153

Post by kenhwang »

noir_lord wrote: post #146
mort96 wrote: post #125

Earlier quoted context omitted.

Got it running with 4800MT/s and literally 30 minute boot times in an AM5 machine. The 30 minute boot time could be worked around by enabling the (off-by-default) memory context restore option in BIOS, but it really made me think something was broken and it wasn't until I found other people talking about 30 minute boot times that I stopped debugging and just let it sit for an eternity. It's so bad. I don't get why th…

You need to enable MCR (which trains the memory once and caches the result for (iirc) 30 days) otherwise yeah, booting is horribly slow, even the 64GB I have can take several minutes but with MCR it boots basically instantly. Some motherboards have it off by default.

Memory training seems to be getting faster with each bios update. In 2024 when I upgraded to AM5, 64GB memory training took like 15 minutes. Now the same setup takes about a minute when it needs to retrain, then near instant with MCR (Windows 11 takes significantly longer to load than the POST process).

Re: AMD's Ryzen 9 9950X3D2 Dual Edition crams 208MB of cache into a single chip

#154

Post by anticensor »

bell-cot wrote: post #68
jaimex2 wrote: post #57

Can someone like... boot Windows 98 on these on a system with no ram?!

Conceptually - yes, easily. But to do it literally - I'm not a low-level motherboard EE, but I'd bet you're looking at 5 to 7 figures (US $) of engineering work, to get around all the ways in which that would violate assumptions baked into the designs of the CPU, support chips, firmwares, etc.

The CPU literally initialises itself without DDR then initialises the DDR PHY, there must be a way of keeping the CPU in that "cache as RAM" mode.

Re: AMD's Ryzen 9 9950X3D2 Dual Edition crams 208MB of cache into a single chip

#155

Post by AnthonyMouse »

SubiculumCode wrote: post #152

Oh man. I am running computations on my server that involve computing geodesic distances with the heat method. The job turns out to be a L3 cache thrasher, leaving my cpus underutilized for multi worker jobs .... 208mb instead of my 25 per socket sounds amazing

They sell essentially the same chips with more CCDs as Epyc instead of Ryzen. 9684X has more than 1GB of L3 per socket (but it's not cheap).

Re: AMD's Ryzen 9 9950X3D2 Dual Edition crams 208MB of cache into a single chip

#157

Post by jazzyjackson »

WD-42 wrote: post #134
secondcoming wrote: post #132

Earlier quoted context omitted.

Your machine takes 30 minutes to boot because of the RAM? Or it takes 30 minutes to load a model?

It's the RAM. It needs to "trained" which takes some time but for for some reason these boards seem to randomly forget their training, requiring it to happen again.

huh, its been a decade since i built a PC, whats changed?

Re: AMD's Ryzen 9 9950X3D2 Dual Edition crams 208MB of cache into a single chip

#158

Post by magicalhippo »

WD-42 wrote: post #134
secondcoming wrote: post #132

Earlier quoted context omitted.

Your machine takes 30 minutes to boot because of the RAM? Or it takes 30 minutes to load a model?

It's the RAM. It needs to "trained" which takes some time but for for some reason these boards seem to randomly forget their training, requiring it to happen again.

I've never had memory training be forgotten with my AM4 nor LPDDR5-based laptops and NUCs. Is this a new thing with AM5 or something? Or just a certain brand of BIOSes?

Re: AMD's Ryzen 9 9950X3D2 Dual Edition crams 208MB of cache into a single chip

#159

Post by alias_neo »

sqquima wrote: post #129
alias_neo wrote: post #95

Earlier quoted context omitted.

In January I upgraded my desktop, 9950X3D £600, 64GB DDR5-6000 £600, MSI MAG Tomahawk X870E £300, Samsung 990 Pro 4TB £350, Asus Prime 9070XT £580. I spent a another £250 on PSU and cooler and reused my case (Phanteks Evolv Enthoo TG, beautiful case but horrible cooling. Will cut some holes in it and if it doesnt work out look for something with more airflow). The RAM price was already inflated at that time, and the…

Very similar config, but I bought a second pair of ram. Running 4 sticks at 3600. Also, the LAN port of the motherboard stopped working after a week, so I had to buy an Ethernet card

Ouch, were you not willing to RMA for that ethernet port? I wouldn't be too pleased after only a week if parts of the board stopped working.

I don't really want to run my RAM that slow which is why I'll probably stick with two sticks.

Re: AMD's Ryzen 9 9950X3D2 Dual Edition crams 208MB of cache into a single chip

#160

Post by WD-42 »

jazzyjackson wrote: post #157
WD-42 wrote: post #134

Earlier quoted context omitted.

It's the RAM. It needs to "trained" which takes some time but for for some reason these boards seem to randomly forget their training, requiring it to happen again.

huh, its been a decade since i built a PC, whats changed?

My guess is bigger numbers, higher voltages, tighter timings.
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