Question Did I make a bad decision? 2 dual channel kits & not listed on mobo QVL

davidbenpark

Honorable
Jun 9, 2014
55
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I just ordered all the parts for my new build. This includes:
  • 32gb of Patriot Viper Steel Series 4000mhz ram made up of of two lots of 2x8gb dual channel kits
  • ASUS Tuf Gaming-Plus x570 Wifi mobo
  • Ryzen 7 3700X
I didn't realise there was a difference between dual channel and quad channel. I also didn't know that XMP might not work out of the box with two dual channel kits, even if they are identical products but just not from the same box. I also didn't realise there was such a thing as a QVL list from the mobo manufacturer until right now, and this ram isn't listed.

Should I expect this to work straight away at the advertised 4000mhz via XMP without manual overclocking/adjusting timings? If not, is manual overclocking ram speed/timings reasonably easy to do? Or should I expect a world of pain, and just return them and go for a safer 2x16gb kit from the QVL list? Am I even asking the right questions?

Thanks a lot in advance for any advice!
 

Rogue Leader

It's a trap!
Moderator
Its tough to give you a definitive answer to this so I'll just make some bullet points and you can decide what you think.
  • You may plug these in and set XMP and it will just work, highly unlikely, especially because they are 4000 mhz, but you could get lucky.
  • Quad channel doesn't exist for Ryzen, however if you were going the route of having 4 DIMMs, buying a quad channel kit is the best choice as it gives you 4 matched DIMMs. In the end you have 2 channels of 2 DIMMs each.
  • Manually overclocking your memory can be tedious, however not impossible. I do think you will have a hard time getting 4000mhz working, but 3733 should be possible. That said there is a chance depending on the kit it just won't play at all.
  • If you haven't opened the package, returning it for a 2x16gb kit on the QVL is the smartest idea. Its the least work, and pain.
So thats what I would do. You MAYBE could make it work, but theres a lot of ways it may not work, and if you can return it and not lose, thats the safe money bet.
 

Rogue Leader

It's a trap!
Moderator
Thanks so much for the really clear advice. I'll return the ram and go for 2x16gb kit as you said - probably at 3600mhz this time, or maybe 3200mhz if XMP can take it up to 3600mhz (not sure if that's how it works but I'm still learning).
No problem, but thats not how XMP works. The simplest way to describe XMP is its a speed profile built into the ram.

So basically DDR4 ram all at a minimum can run at 2133 mhz. If you just put the ram in and go thats what it will run at (or 2400 depending on the platform but thats irrelevant). Anything over those speeds is "overclocked". Youi need to go to the BIOS and turn on the equivalent XMP profile built into the ram to get it to ruin the speed on the box, if its over those stock speeds. Or manually overclock it. Technically all ram is the same thing, its just that the chips are tested and binned based upon how much they can take. So, for example, ram sold to you as DDR4-3000 was tested stable to 3000mhz and has the XMP profile built in that will run it at that speed. There are no higher profiles aboard thats it.

Now if you want to get really technical, you could probably sit there and manually overclock it higher if you want. But they don't just print those numbers on the package for their health, and its a tedious time consuming process to get it to go higher, if its even possible.

So in closing, buy the ram in the speed you want. Right now the sweet spot for Ryzen 3xxx chips is 3733 MHZ, thats what you should be looking for.
 
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Karadjgne

Titan
Herald
Channels aren't sticks. On your motherboard is 4 slots, 2x for Channel A and 2x for Channel B (A1, A2/B1, B2). So the best you can do is dual channel, whether you use 2sticks or 4sticks. You won't find Quad Channel until you move to the Intel HEDT motherboards like lga2011-3 or 2066.

Ryzen cpus themselves aren't fond of 4 stick usage at speeds over 2400MHz. Has to do with the Infinity Fabric that Ryzens use to communicate between the cores. The Infinity Fabric speed is based on ram speeds, and it gets a little hectic trying to stabilize 4 different sticks if they run fast.

So 2x sticks of the speed you want above 2400MHz is far better for Ryzen in general.

The other side of that is the ram itself. It's made from sheets of silicon and no 2 sheets are identical. They each have slightly different impurities, more aluminium, more copper, more nickle etc. When you buy ram, you'll see the 5 primary timings, the 16-18-18-36 2T. While the most important they are also the broadest, many sticks will have exactly the same primaries. However, there's also over 40 secondary and tertiary timings that aren't advertised or generally seen. And that's what the impurities affect the most.

So while you can have 2 exactly the same ram, same model, speed, vendor, color, timings, size, they may end up totally incompatible because the secondary and tertiary timings are so out of sync.

When you buy a kit with 4x sticks, the factory has tested those 4 sticks and guarantees that all 4 will work together in sync. When you buy 2x kits of 2x sticks, there's no guarantee at all than any of the sticks will work on a different kit, you become the tester. It's not that the kits are bad, they both work seperately just fine, they just don't work together. This is why 4 stick kits cost more than 2x2stick kits, the additional testing that could range to finding 1 stick in the last million made that's compatible with the other 3.

So mixing kits is a bad idea. Better to buy a 4stick kit, factory tested.

But you are better with a 2x stick kit, it's a Ryzen.
 

davidbenpark

Honorable
Jun 9, 2014
55
3
10,535
1
Its tough to give you a definitive answer to this so I'll just make some bullet points and you can decide what you think.
  • You may plug these in and set XMP and it will just work, highly unlikely, especially because they are 4000 mhz, but you could get lucky.
  • Quad channel doesn't exist for Ryzen, however if you were going the route of having 4 DIMMs, buying a quad channel kit is the best choice as it gives you 4 matched DIMMs. In the end you have 2 channels of 2 DIMMs each.
  • Manually overclocking your memory can be tedious, however not impossible. I do think you will have a hard time getting 4000mhz working, but 3733 should be possible. That said there is a chance depending on the kit it just won't play at all.
  • If you haven't opened the package, returning it for a 2x16gb kit on the QVL is the smartest idea. Its the least work, and pain.
So thats what I would do. You MAYBE could make it work, but theres a lot of ways it may not work, and if you can return it and not lose, thats the safe money bet.
Thanks so much for the really clear advice. I'll return the ram and go for 2x16gb kit as you said - probably at 3600mhz this time, or maybe 3200mhz if XMP can take it up to 3600mhz (not sure if that's how it works but I'm still learning).
 

davidbenpark

Honorable
Jun 9, 2014
55
3
10,535
1
No problem, but thats not how XMP works. The simplest way to describe XMP is its a speed profile built into the ram.

So basically DDR4 ram all at a minimum can run at 2133 mhz. If you just put the ram in and go thats what it will run at (or 2400 depending on the platform but thats irrelevant). Anything over those speeds is "overclocked". Youi need to go to the BIOS and turn on the equivalent XMP profile built into the ram to get it to ruin the speed on the box, if its over those stock speeds. Or manually overclock it. Technically all ram is the same thing, its just that the chips are tested and binned based upon how much they can take. So, for example, ram sold to you as DDR4-3000 was tested stable to 3000mhz and has the XMP profile built in that will run it at that speed. There are no higher profiles aboard thats it.

Now if you want to get really technical, you could probably sit there and manually overclock it higher if you want. But they don't just print those numbers on the package for their health, and its a tedious time consuming process to get it to go higher, if its even possible.

So in closing, buy the ram in the speed you want. Right now the sweet spot for Ryzen 3xxx chips is 3733 MHZ, thats what you should be looking for.
Thanks again - this advice is really useful. I think I'm fully clued up on the RAM kit selection and using XMP now as I'll just keep it simple and go for 2x16gb (even though it costs a fortune!).

One quick question out of interest though if you have a minute. Is there a well-known issue with using two dual channel kits together instead of one quad? Is it less likely to work with XMP? Or does it also limit that chances of a manual overclock working?
 

davidbenpark

Honorable
Jun 9, 2014
55
3
10,535
1
Channels aren't sticks. On your motherboard is 4 slots, 2x for Channel A and 2x for Channel B (A1, A2/B1, B2). So the best you can do is dual channel, whether you use 2sticks or 4sticks. You won't find Quad Channel until you move to the Intel HEDT motherboards like lga2011-3 or 2066.

Ryzen cpus themselves aren't fond of 4 stick usage at speeds over 2400MHz. Has to do with the Infinity Fabric that Ryzens use to communicate between the cores. The Infinity Fabric speed is based on ram speeds, and it gets a little hectic trying to stabilize 4 different sticks if they run fast.

So 2x sticks of the speed you want above 2400MHz is far better for Ryzen in general.

The other side of that is the ram itself. It's made from sheets of silicon and no 2 sheets are identical. They each have slightly different impurities, more aluminium, more copper, more nickle etc. When you buy ram, you'll see the 5 primary timings, the 16-18-18-36 2T. While the most important they are also the broadest, many sticks will have exactly the same primaries. However, there's also over 40 secondary and tertiary timings that aren't advertised or generally seen. And that's what the impurities affect the most.

So while you can have 2 exactly the same ram, same model, speed, vendor, color, timings, size, they may end up totally incompatible because the secondary and tertiary timings are so out of sync.

When you buy a kit with 4x sticks, the factory has tested those 4 sticks and guarantees that all 4 will work together in sync. When you buy 2x kits of 2x sticks, there's no guarantee at all than any of the sticks will work on a different kit, you become the tester. It's not that the kits are bad, they both work seperately just fine, they just don't work together. This is why 4 stick kits cost more than 2x2stick kits, the additional testing that could range to finding 1 stick in the last million made that's compatible with the other 3.

So mixing kits is a bad idea. Better to buy a 4stick kit, factory tested.

But you are better with a 2x stick kit, it's a Ryzen.
Awesome! Thanks for the really detailed answer. It always feels better when you fully understand decisions before you make them.
 

Rogue Leader

It's a trap!
Moderator
So while you can have 2 exactly the same ram, same model, speed, vendor, color, timings, size, they may end up totally incompatible because the secondary and tertiary timings are so out of sync.
To add to this, in some cases you can buy 2 identical packages of ram and they have completely different brands of DRAM chip in them. Specced exactly the same, but different. Its happened many times in the past except when you're buying the highest end product.
 

Karadjgne

Titan
Herald
I watched a video a while back, dude was de-heatsinking a 4 pack kit of Patriot ram in order to put the RGB sleeve on them. Same kit, 2x sticks SkHynix, 2x Samsung, the SK was 8x512Mb, the Samsung 4x1Gb IC'S. About as far away from similar as its possible to get in a 4x4Gb kit, but they worked just fine. Factory tested.

It happens when vendors go with new contracts from whomever guarantees a certain amount of ic's, at the cheapest price, yet still retains the timings required. If you look at gskill, the RipJaws in particular, many times the blue series had far better timings than red, but is equitable in price. Chalk that upto demand for red, and not blue ram. But normally color doesn't make any difference.
 
Reactions: davidbenpark

davidbenpark

Honorable
Jun 9, 2014
55
3
10,535
1
I watched a video a while back, dude was de-heatsinking a 4 pack kit of Patriot ram in order to put the RGB sleeve on them. Same kit, 2x sticks SkHynix, 2x Samsung, the SK was 8x512Mb, the Samsung 4x1Gb IC'S. About as far away from similar as its possible to get in a 4x4Gb kit, but they worked just fine. Factory tested.

It happens when vendors go with new contracts from whomever guarantees a certain amount of ic's, at the cheapest price, yet still retains the timings required. If you look at gskill, the RipJaws in particular, many times the blue series had far better timings than red, but is equitable in price. Chalk that upto demand for red, and not blue ram. But normally color doesn't make any difference.
That's really interesting - didn't imagine two sticks of the same RAM could be so different.

Was it just sheer luck then that they worked together?
 

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