[SOLVED] Upgrading CPU with current motherboard & memory; good or bad idea?

Sep 22, 2021
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My PC is Ryzen 7-1700 CPU with Asus Prime X370-Pro MB, Seasonic X750 PS & 16Gb of DDR4 memory. According to ASUS, a Ryzen 9-3900 & 3900X are compatible with the Prime X3700-Pro MB. I'm not a gamer but I do lots of photo & video rendering.

My question is if this is a good idea?
 
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... With the BIOS update, should an upgrade to a 3900X go smoothly?
Since you've updated BIOS to a supporting one it should go OK...but nothing is guaranteed in this world. Maybe death. And taxes.

When you're ready for the exchange be sure to reset CMOS after installing the new processor, that's the number one thing people fail to do and then have stability problems. Also check MSConfig...Boot tab...Advanced Options and make sure the check box beside Number of Processors is cleared. It sometimes get set to the number of the previous CPU's threads.

Heat is a concern as Ryzen is thermally sensitive...keeping the CPU cooler means it boosts higher and longer. So if you haven't yet, consider getting a really good cooler to reap...
Sep 22, 2021
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Thanks. I checked my BIOS & it is up to date for either of these. I was leaning towards the 3900 because it has the same Thermal Design Power of 65W as my Ryzen 7-1700. The 3900X is 105W but faster.
 
Thanks. I checked my BIOS & it is up to date for either of these. I was leaning towards the 3900 because it has the same Thermal Design Power of 65W as my Ryzen 7-1700. The 3900X is 105W but faster.
B350's were pretty weak overall as well as many X370's but your's (Asus Prime X370 -Pro )is a bit of an exception. It's CPU VRM is built of 6 true phases of NexFET 40A power blocks. And from what I can tell it appears to have the power blocks under a proper good heatsink so they should never have occasion to hit their rated 150C operating temp either. It should handle a 3900X well enough, probably even a 3950X. I wouldn't try fixed all-core, but that rarely pays off with Zen 2 or Zen 3 CPU's anyway
 
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punkncat

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There were more than a few X370 boards that were very well designed with more than ample power delivery. Many of us whom bought into those boards are significantly more than disappointed in the lack of BIOS revisions allowing 5xxx Ryzen. Every generation/chipset has good and bad boards and to make a statement that they "weren't built as well" is an erroneous blanket response.
 
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... Many of us whom bought into those boards are sigificantly more than disappointed in the lack of BIOS revisions allowing 5xxx Ryzen. ...
I've read some 300 series boards got Ryzen 5000 SMU's. Asrock was one...but I would not be surprised if Asus didn't. Asus is known for pushing the limits with AMD (they fully enabled PCIe gen 4 on 400 chipsets until AMD pulled it from AGESA).
 
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punkncat

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I've read some 300 series boards got Ryzen 5000 SMU's. Asrock was one...but I would not be surprised if Asus didn't. Asus is known for pushing the limits with AMD (they fully enabled PCIe gen 4 on 400 chipsets until AMD pulled it from AGESA).

As I understand these are unauthorized revisions and sort of a "at your own risk" type thing. Given the age of the motherboard probably not a big deal in itself, but certainly not something that I personally would risk in the cost of the higher end CPU. Reading indicates that the majority of this use and recommendation surrounds the R5 variant. I continue to keep up with reading on the subject, of which hasn't resulted in my confidence that risking a working system to try is worthwhile at this current time. IMO the cost of 3xxx isn't worth moving to for the performance as opposed to 2xxx and (as above) 5xxx is still a gamble.
 
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As I understand these are unauthorized revisions and sort of a "at your own risk" type thing. ...
There's a utility called "SMU Checker" you can find. Drop a board BIOS binary file on it and it looks for the SMU's included. Look for a Vermeer SMU...if it has one, high probability of success.

So if I had the board OP has and it's BIOS indicates a Vermeer SMU is present, and was fully committed on going to a 5900X for performance reasons, I'd give it a try before buying a 500 series board...unless I also wanted the (specious) PCIe gen 4 advantage.

The only issue I can see is with the chipset driver installer: if it sees a 300 series chipset I wonder if it installs everything to support a 5000 CPU? Like CPPC2 support?
 
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Sep 22, 2021
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I would probably choose the 3900, as X370 boards were not built as well, as say B450 and B550.
I destroyed a MB with some of my long video renders. :) That's why I was leaning to the 3900 with its 65W instead of the 3900X at 105W. When I render recently my CPU peaked at 53C. A new 3900 with the same 65W probably would be a little warmer but far less than a 105W CPU like the 3900X.
 
Sep 22, 2021
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So I just realized, you can't buy the 3900 since it's OEM only (maybe eBay might have some used ones). However, you can set the 3900X to behave like a 65W TDP CPU by either limiting its PPT or using Eco Mode.

The 3900 can be purchased now at a few retailers at a premium. About $100 more than the faster 3900X!
 
... When I render recently my CPU peaked at 53C...

Do not confuse 'temperature' with 'power consumption' or thermal output. TDP ratings (the 65w and 105w numbers I assume) are no indication of either of those ... power consumption isn't considered in the formula for calculating it. Ryzen's a remarkably energy efficient processor and both power consumption and thermal output is much smaller than most people realize.

Ryzen's temperatures are a by-product of the very small (7nm) geometry, large number of on-die sensors, hot-spot temp reporting and an aggressive boosting algorithm
 
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Sep 22, 2021
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The only reason I considered the Ryzen 3900 to replace the Ryzen 1700 was the TDP matched at 65W. I assumed wrongly that 3900X at 105W meant much more heat. But the 3900 is harder to find plus more expensive than the faster 3900X; about $100.

The 3900X is on my MBs (ASUS X370 Pro) approved, compatible list & I have updated my BIOS to match an upgrade. Should heat be a concern? With the BIOS update, should an upgrade to a 3900X go smoothly?
 
... With the BIOS update, should an upgrade to a 3900X go smoothly?
Since you've updated BIOS to a supporting one it should go OK...but nothing is guaranteed in this world. Maybe death. And taxes.

When you're ready for the exchange be sure to reset CMOS after installing the new processor, that's the number one thing people fail to do and then have stability problems. Also check MSConfig...Boot tab...Advanced Options and make sure the check box beside Number of Processors is cleared. It sometimes get set to the number of the previous CPU's threads.

Heat is a concern as Ryzen is thermally sensitive...keeping the CPU cooler means it boosts higher and longer. So if you haven't yet, consider getting a really good cooler to reap it's fullest benefits. Also something to consider is good case ventilation with proper fans in front and top/rear to push cool air in and hot air out.
 
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Solution
Sep 22, 2021
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Since you've updated BIOS to a supporting one it should go OK...but nothing is guaranteed in this world. Maybe death. And taxes.

When you're ready for the exchange be sure to reset CMOS after installing the new processor, that's the number one thing people fail to do and then have stability problems. Also check MSConfig...Boot tab...Advanced Options and make sure the check box beside Number of Processors is cleared. It sometimes get set to the number of the previous CPU's threads.

Heat is a concern as Ryzen is thermally sensitive...keeping the CPU cooler means it boosts higher and longer. So if you haven't yet, consider getting a really good cooler to reap it's fullest benefits. Also something to consider is good case ventilation with proper fans in front and top/rear to push cool air in and hot air out.

There is one last BIOS update that ASUS offered that I have not installed (don't fix what isn't broke) but the update for 2nd & 3rd gen Ryzen's is installed. It may not be a bad idea to go ahead & install that last update.

If I recall correctly, the 1st gen Ryzen CPU / MB combo were fussy about accepting RAM. What I was assured by online store to be fine had to be exchanged for RAM approved on the ASUS list.

The Ryzen 1700 is 8 core, 3900X is 12 so probably some changes in the BIOS Processor box.

Will I need any of my passwords after resetting CMOS? And, will Microsoft need to be called because a detected change of hardware? I don't want to be surprised by not having that & other info.
 
There is one last BIOS update that ASUS offered that I have not installed (don't fix what isn't broke) but the update for 2nd & 3rd gen Ryzen's is installed. It may not be a bad idea to go ahead & install that last update.

If I recall correctly, the 1st gen Ryzen CPU / MB combo were fussy about accepting RAM. What I was assured by online store to be fine had to be exchanged for RAM approved on the ASUS list.

The Ryzen 1700 is 8 core, 3900X is 12 so probably some changes in the BIOS Processor box.

Will I need any of my passwords after resetting CMOS? And, will Microsoft need to be called because a detected change of hardware? I don't want to be surprised by not having that & other info.
I suggest updating to the latest BIOS. Reason has more to do with compatibility with upcoming Win11 but there could be more 'fixes' that improve memory compatibility and other things. Those memory QVL's are of more value when first buying RAM, but they're hardly exclusive. I would not have exchanged RAM until trying it with the new CPU and latest BIOS...unless there were also other benefits desired, like increasing capacity or higher speed RAM.

You do not have to make any changes in BIOS other than the CMOS reset. When it boots first time after a CMOS reset it identifies and initializes the processor and re-trains for memory. That's why a CMOS reset is needed after any BIOS updates and CPU or memory changes as it forces that process to occur.

A CMOS reset will change none of your passwords in Windows. It will clear any BIOS level passwords if you had one established though...that's why they're pretty much worthless unless you've also physically secured the computer in a locked cabinet. Changing a processor and updating BIOS can be a problem if you're running a bitlocker encrypted drive though.
 
Sep 22, 2021
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Thanks!
I suggest updating to the latest BIOS. Reason has more to do with compatibility with upcoming Win11 but there could be more 'fixes' that improve memory compatibility and other things. Those memory QVL's are of more value when first buying RAM, but they're hardly exclusive. I would not have exchanged RAM until trying it with the new CPU and latest BIOS...unless there were also other benefits desired, like increasing capacity or higher speed RAM.

I will update.
I didn't explain clearly that when I built the PC 4 years ago is when I had the issue with RAM & replaced it with RAM on the QVL list.

I have considered increasing RAM from 16Gb to 32Gb. Todays QVL looks pretty much the same as 4 years ago. Not sure if updating the CPU would require selecting only from what's on the QVL or not. I may need to contact ASUS about that.
 
Thanks!


I will update.
I didn't explain clearly that when I built the PC 4 years ago is when I had the issue with RAM & replaced it with RAM on the QVL list.

I have considered increasing RAM from 16Gb to 32Gb. Todays QVL looks pretty much the same as 4 years ago. Not sure if updating the CPU would require selecting only from what's on the QVL or not. I may need to contact ASUS about that.
While the motherboard mfr. QVL is a list of memory that's been tested with the motherboard (or so one assumes) it's the processor that has the most important part for ensuring compatibility, the integrated memory controller.

AMD's published a QVL too...
 
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Sep 22, 2021
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Today I ordered the AMD Ryzen 3900X to replace the Ryzen 1700. It should arrive next week. Here's a list of what I have done to prepare for the change. Please advise if I have overlooked anything.
  1. I have updated the ASUS X370 Pro MB BIOS to the latest available that includes updates for Windows 11.
  2. I have also updated the MB's AMD chipset to the latest (drivers?) but may need to do this again once the 3900X is installed.
  3. As recommended I will clear the MB CMOS by shorting the CMOS pins & also removing the battery for a few minutes.
  4. I checked in BIOS/Security & BIOS isn't a password protected. I was concerned that I may have set a password when building the PC 4 years ago but didn't.
  5. I don't know if MS will flag me because of the change of hardware. I'm prepared if they do.
 
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