Question RAM options and PSU question

Nov 6, 2019
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1. What long-term RAM details should I care about? If I get a 2x16GB (32GB) kit today and add 2x8GB (16GB) or 2x16GB (32GB) later, what problems happen? Do some high clock speed DIMMs not function right at lower clock speeds? I understand that mixing RAM kits can cause problems but do those problems only affect speed?
If I bought a higher speed RAM and added a second kit that slowed it down, would it be slowed down by less than if I had originally bought a set of lower speed RAM? My motherboard is dual channel so I want to work in groups of 2-stick kits.

2. I've always planned to get an aftermarket fan cooler. Having it be quieter and colder than a stock cooler was my goal. Now that I've changed my plans to the i7-9700k instead of the i7-9700 I'm realizing that I don't know how to compare coolers. What would be a reliable cooler for an i7-9700k that is never over clocked?
If years later I upgraded to a used i9-9900k that I didn't overclock how much extra would I have to pay for a cooler that could handle that?


3. I keep reading here about the M12ii & M12iii PSU and how people have different model names for this same central template of PSU. This worries me and makes me expect to find this kind of info on the store page of a power supply. My plan was to compute my total power supply, add couple of extra watts, add 30%, and then get a close match from a big name brand like Corsair. What else do I have to look out for? How do I tell if any given PSU is reliable?

Here are my specs, goals, and budget:
I'm building a machine to take on various video editing and coding projects. I'm already set as far as gaming is concerned. Because I might need 32GB of RAM for video editing I've decided on getting 2x16GB sticks now instead of starting at half and upgrading when I need it. My budget is $1,200 but I'm willing to go over that by a couple hundred if I need to. I already own all the accessories I need. I am a USA buyer if that's relevant. I will be doing no SLI and no overclocking. I will be running everything at 1920x1080. I am more concerned with my machine lasting 5 to 8 years than I am with future-proofing it.

CPU: Intel Core i7-9700K Coffee Lake 8-Core 3.6 GHz (4.9 GHz Turbo) LGA 1151 (300 Series) 95W BX80684I79700K Desktop Processor Intel UHD Graphics 630
https://www.newegg.com/core-i7-9th-gen-intel-core-i7-9700k/p/N82E16819117958

CPU Cooler: Noctua NH-D15S 140mm SSO2 D-Type Premium CPU Cooler, NF-A15 PWM Fans
https://www.newegg.com/p/N82E16835608072

Motherboard: GIGABYTE Z390 AORUS PRO LGA 1151 (300 Series) Intel Z390 HDMI SATA 6Gb/s USB 3.1 ATX Intel Motherboard
https://www.newegg.com/p/N82E16813145098
https://www.gigabyte.com/Motherboard/Z390-AORUS-PRO-rev-10/support#support-manual

GPU: SAPPHIRE PULSE Radeon RX 5700 DirectX 12 100417P8GL 8GB 256-Bit GDDR6 PCI Express 4.0 x16 ATX Video Card
https://www.newegg.com/sapphire-radeon-rx-5700-100417p8gl/p/N82E16814202350

PSU: Will be at minimum 30% higher than 97 watts above the final wattage rating of my parts with at least an 80% rating from a brand I can trust.

Memory: 2x16GB to be ran as Dual Channel. I can't imagine needing more RAM than 32GB but I want to stay flexible enough to upgrade.

Storage: 1TB of SSD storage as a boot drive with separate HDD storage added after the system is built.


I made a previous thread asking different questions. I've changed my build slightly but here it is for redundant reference. All the important info is already here. https://forums.tomshardware.com/threads/are-these-parts-strong-enough-for-video-editing-im-bad-with-gpus.3542130/
 
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ScrewySqrl

Champion
Moderator
Unless you are looking at Workstation level rendering/compute tasks, just 32 Gb should be fine (2x16), If you really need 64, a 4x16 might be cheaper than 2x32 right now, and would still be dual channel - just 2 dual channels.

As far as PSU goes, my rule of thumb is at least 100W more than the minimum you need, rounded up to the nearest 50W So if your system uses, say 384W, I round that up to 400W, and say 500W is a good bet, but no higher than double the base wattage for best efficiency, so on that example, it would be 500W minimum, and 750W Maximum (2x384=768W)
 
Nov 6, 2019
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Unless you are looking at Workstation level rendering/compute tasks, just 32 Gb should be fine (2x16), If you really need 64, a 4x16 might be cheaper than 2x32 right now, and would still be dual channel - just 2 dual channels.

As far as PSU goes, my rule of thumb is at least 100W more than the minimum you need, rounded up to the nearest 50W So if your system uses, say 384W, I round that up to 400W, and say 500W is a good bet, but no higher than double the base wattage for best efficiency, so on that example, it would be 500W minimum, and 750W Maximum (2x384=768W)
I'll keep what you said in mind about the PSU. My biggest question isn't about RAM size but how to pick parts and what I can pick from. I don't know if I'm backed into a corner with RAM options, if PCPartPicker has let me down, or what other resources are out there. I have the Qualified Vendors List for my motherboard but I do not understand it.
 

PC Tailor

Distinguished
Herald
The QVL for your motherboard simply lists all of the RAM modules that they have tested on their board and in what configuration. But it by no means shows you what isn't compatible, as there are many more modules perfectly compatible with that board than the QVL states.

Usually the better option is to visit the RAM manufacturer website and check what boards they have tested them on, the onus is much heavier on RAM manufacturers to test boards rather than the adverse.

But generally with RAM, as long as it is pretty much the correct config (size, speed, type, from the same pack etc.) then generally there is not much room to go wrong. Where it often does go wrong is mixing modules, picking RAM modules of speeds that the MB does not support (which doesn't necessarily stop it from working) and using all 4 DIMMS as not all motherboard deal well with all 4 DIMMS populated

Also just remember on the PSU, good brand does not equal good quality! Cooler Master and EVGA for example make a ton of trash PSUs.
 
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Nov 6, 2019
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When I settled on a cooler all my PCPartPicker RAM problems went away. I've decided on the Noctua NH-D15S. It's quiet, it's extra cold, it should fit, it's not too pricey at $80, and I think that if I upgraded my CPU it would still work well.

I am still uncertain about what RAM to buy. I updated the OP with my new question so I'll repost that here. My goal is to start off with 32GB of RAM and then add 16GB or 32GB if I were to ever need it. My motherboard is dual channel so I want to work in groups of 2-stick kits.

I'm wondering about what RAM details matter long-term. If I get a 2x32GB kit today and add 2x16GB or 2x32GB later, what problems happen? Do some high clock speed DIMMs not function right at lower clock speeds? I understand that mixing RAM kits can cause problems but do those problems only affect speed?
If I bought a higher speed RAM and added a second kit that slowed it down, would it be slowed down by less than if I had originally bought a set of lower speed RAM?
 

PC Tailor

Distinguished
Herald
I'm wondering about what RAM details matter long-term. If I get a 2x32GB kit today and add 2x16GB or 2x32GB later, what problems happen?
RAM is only guaranteed in the form sold (from the same physical pack) as the manufacturing process is very delicate and also changes frequently, so technically you could buy 2 packs of the exact same model RAM, and they may not work together. Not saying it never works, it's just a gamble.

I understand that mixing RAM kits can cause problems but do those problems only affect speed?
If one set of RAM modules are a different speed then most systems will downclock the other RAM to the lowest denominator, so if you pair 3200 with 2400, they'll likely all downclock to 2400.
 
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RAM is only guaranteed in the form sold (from the same physical pack) as the manufacturing process is very delicate and also changes frequently, so technically you could buy 2 packs of the exact same model RAM, and they may not work together. Not saying it never works, it's just a gamble.


If one set of RAM modules are a different speed then most systems will downclock the other RAM to the lowest denominator, so if you pair 3200 with 2400, they'll likely all downclock to 2400.
You've hit the nail on the head. That's what I don't get. In what way exactly would those two RAM modules of the same specifications fail to work together? I read that all the time here but almost nowhere when I look stuff up. What goes wrong?

And then about the lowest denominator. I would naturally try mixing using the same specs but what I'm wondering about in your scenario is if it's possible for both RAM sticks to be reduced because the higher speed one can't slow down to match the speeds of the lower speed one. Is it possible that the "highest" lowest common denominator can't be reached and an even lower one is used instead?
 

PC Tailor

Distinguished
Herald
The manufacturing of RAM (and almost any PCB or chip) is actually a very delicate process, it is performed in very highly regulated clean rooms, and the material that goes into those components are also very delicate to change.

Each chip is cut out of silicon, and that silicon can be prone to various impurities or contamination even simply from dust, which can affect the compatibility of the modules. The point being, is they pre-determine the modules that will go in a pack, manufacture accordingly, and then test them on a system together at the end, so by all accounts, there are no guarantees thereafter.

You can actually buy 2 of the EXACT SAME MODEL RAM, but from 2 different packs, and they can (and have) not be compatible - because in a sense, they might not be the exact same RAM.

So does it not work all of the time? No, there are plenty of times where it does work.
But is it a gamble? Absolutely yes.

if it's possible for both RAM sticks to be reduced because the higher speed one can't slow down to match the speeds of the lower speed one.
The higher RAM will usually just downclock to the slower RAM, and that's not because of the RAM per se, but more to do with the memory controllers management of that RAM. It becomes difficult to manage and get stability when they are both operating differently.

It tends to come from what speeds the board can operate at, not what the RAM operates at.
 
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Nov 6, 2019
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You can actually buy 2 of the EXACT SAME MODEL RAM, but from 2 different packs, and they can (and have) not be compatible - because in a sense, they might not be the exact same RAM.

So does it not work all of the time? No, there are plenty of times where it does work.
But is it a gamble? Absolutely yes.
If my gamble goes poorly, what happens?

OS Instability? BSODs? Memory loss errors? Memory corruption errors? Does it fail early? Does it run in single channel mode instead of dual channel? Is it not recognized by BIOS and/or Windows? What exactly goes wrong?
 

PC Tailor

Distinguished
Herald
With mixed RAM, usually one of 2 things will happen:
  • The PC will not boot at all.
  • The PC will work normally.
Other things that can happen:
  • Various stop errors (BSOD in Windows)
  • General instability.
  • Random restarts in worse instability.
  • Not being recognised.
Generally i would say it's more common for mixed RAM to work together assuming they are matched in every other respect, but this is simply a way of minimising risk, and certainly does not eliminate the risk.

The single/dual channel will tend to be about how they are installed in the MB slots as one pair of slots will be allocated one channel to the CPU.
 
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