Question RAM XMP worked fine before I changed CPU and GPU, now PC won't POST with XMP enabled ?

[Scallywags]

Hi, hoping someone can point me in the right direction. My RAM was running fine with XMP enabled before I did some upgrades to my kid's gaming PC over the weekend. The new parts went in just fine and everything was all good until I tried to enable XMP on the RAM with the new parts. When I enable XMP the machine won't POST. I clear CMOS and it boots just fine without XMP enabled, but every time I enable XMP it fails to post.

I updated the BIOS to the latest rev, then started the memory testing steps in the sticky here. I pulled out 1 stick and left one in the A2 slot, enabled XMP and adjusted the voltage in increments from 1.2 to 1.3 but it failed to post every time. Since I know the memory can post in XMP I thought it made sense to ask here before I go through every pain-staking step that article...

Parts that stayed the same:
ASRock B450M Mobo
Corsair Vengeance LPX 16GB (2x 8GB ) DDR4-2400 CL16
500W PSU

Parts that changed:
Ryzen 5 3500 ---> to Ryzen 7 5700
NVIDIA 1650 Super ---> ASRock Radeon RX 6600

 

[Darkbreeze]

What speed is the memory configuring itself for after you clear CMOS?

What is the EXACT model of your "500w PSU" and how long has that unit been in service since it was new? Technically you're underpowered for the RX 6600 but I'd think it would still POST unless it's a pretty terrible model, which is very much might be at "500w" since there are extremely few IF any 500w models out there in the last, IDK, five to eight years, maybe longer, that were any good. Almost every decent power supply model out there during that period was an increment of 50. 450w, 550w, 650w, 750w, etc. There are a very few exceptions but most of those are much older models that wouldn't be trustworthy anymore anyhow.

Have you tried setting XMP and then before saving settings and restarting, increasing the DRAM voltage by a small amount (Whatever the smallest increment is that your motherboard will allow.) and repeating that, increasing each time it fails to POST, a few times? As outlined in my guide you linked?

You might also very much want to pull the CPU and check for bent pins. In my experience when a system WORKS at the XMP setting and then doesn't after removing the CPU for whatever reason, VERY often it's because a pin or two has been inadvertently bent.

 

[Scallywags]

What speed is the memory configuring itself for after you clear CMOS?

What is the EXACT model of your "500w PSU" and how long has that unit been in service since it was new? Technically you're underpowered for the RX 6600 but I'd think it would still POST unless it's a pretty terrible model, which is very much might be at "500w" since there are extremely few IF any 500w models out there in the last, IDK, five to eight years, maybe longer, that were any good. Almost every decent power supply model out there during that period was an increment of 50. 450w, 550w, 650w, 750w, etc. There are a very few exceptions but most of those are much older models that wouldn't be trustworthy anymore anyhow.

Have you tried setting XMP and then before saving settings and restarting, increasing the DRAM voltage by a small amount (Whatever the smallest increment is that your motherboard will allow.) and repeating that, increasing each time it fails to POST, a few times? As outlined in my guide you linked?

You might also very much want to pull the CPU and check for bent pins. In my experience when a system WORKS at the XMP setting and then doesn't after removing the CPU for whatever reason, VERY often it's because a pin or two has been inadvertently bent.

Memory default is 2133mhz at 1.2V adjustable in .01V increments. I did go down to 1 stick in the A2 slot, put in XMP and adjust voltage by .01V increments up to 1.3V. Oddly the closest I got to a post was at 1.21V when it at least displayed the ASRock logo, but it got stuck there.

PSU was bought second hand - Masterwatt Lite 500W with 80 Plus Certified Power Supply with Full Protections by Cooler Master Model: MPX-5001-ACAAW

CPU is brand new and I inspected the pins before install. I suppose it's possible I bent one during install it went into the socket without any problem. Is it a high possibility of a bent pin or is that a suggestion to check if all else fails?

 

[JayGau]

2400 MHz CL16 is a very slow kit. DDR4 can easily run at 3600 MHz and CL16. The 5700X should definitely run with this RAM.

But you need to be careful here: how long do you wait before giving up and conclude that it doesn't POST? If you replace the CPU and enable DOCP, the board might have to train itself for several minutes before booting.

You also have one of the cheapest boards on the market and your PSU is not only on the limit for power, but also total crap. Masterwatt Lite are rated tier F and should be avoided at all cost. This could cause problems when you switch to a more powerful CPU.

 

[JayGau]

What PSU would you recommend for the RX 6600? IMO swapping out the PSU is less effort/risk than pulling the CPU so I might start there if I need more power to push the GPU anyway.

You need at least 650 W to have some headroom with this system. And rule number one is to never cheap out on the PSU. Get one from a well known brand, don't aim for the lowest price and don't buy used.

According to Tom's Hardware, the MSI MAG A650BN is one of the best options for those who don't want to break the bank. The Corsair RM650X is also a very good PSU but it's hard to find in stock right now (but you could go for a RM750X). The Corsair CX650M is a lower tier one but still good (I habe been running one for 8 years without any issues). Seasonic and Evga also have good 650 W options.

 

[Scallywags]

Damn, so much for saving a few bucks on a PSU. I thought being a reputable brand like Cooler Master it was OK. I was looking at the MSI MAG A650BN against the Segotep 650W 80 Plus Gold Certified PSU. The MSI is Bronze certified while this Segotep is Gold, does that really matter?

I waited 5+ minutes for the system to post after the XMP settings were changed.

 

[JeffreyP55]

Damn, so much for saving a few bucks on a PSU. I thought being a reputable brand like Cooler Master it was OK. I was looking at the MSI MAG A650BN against the Segotep 650W 80 Plus Gold Certified PSU. The MSI is Bronze certified while this Segotep is Gold, does that really matter?

I waited 5+ minutes for the system to post after the XMP settings were changed.

Cool Master is "Cool" You purchased the wrong power supply to power your PC. Like somebody mentioned. 650w will do it.

 

[JayGau]

Damn, so much for saving a few bucks on a PSU. I thought being a reputable brand like Cooler Master it was OK. I was looking at the MSI MAG A650BN against the Segotep 650W 80 Plus Gold Certified PSU. The MSI is Bronze certified while this Segotep is Gold, does that really matter?

I waited 5+ minutes for the system to post after the XMP settings were changed.

Bronze vs gold is about the power efficiency, not the quality. You might save a few bucks a year with the gold rated PSU but it doesn't mean the bronze one is not good (and you can get a crappy gold PSU too). And I would personally not put a Segotep in my own PC. It's very hard to find any reliable pro reviews for these and the fact that it's a Chinese based manufacturer may be an issue if there's a problem and you need to RMA.

It can take up to 15-20 minutes for the board to finish training. But with this PSU in the PC I would not wait that long.

 

[Darkbreeze]

Masterwatt Lite is pure and complete garbage. I'm not exaggerating or being an elitist who thinks everybody has to have a top 10% PSU. It's simply garbage. You seriously want to replace that unit before it causes any damage to the rest of your system.

Brands have nothing to do with quality. Efficiency (Gold, bronze, etc.) have very little to do with quality. MODEL is where you determine quality and you do that by looking at professional reviews. If there is no professional review of a PSU model that has been out longer than six months you absolutely want to avoid that model 90% of the time.

Also, the memory you have, Corsair LPX is WELL KNOWN to NOT "play nice" with Ryzen chipsets/CPUs. The fact that it worked before you changed CPUs doesn't much change that. You changed processors, enough said on that. I've seen only a handful of Ryzen systems that would work with an LPX memory kit installed out of hundreds of builds. And, as mentioned above, that is a VERY SLOW kit for the components you have. A 3600 MT/s kit is what you want.

I'd shoot for something like this. Yes there are less expensive power supplies that are somewhat better than yours but with only about a twenty dollar difference between them, and they are STILL VERY MEDIOCRE models, and this, this is the very best option available right now under 100 dollars regardless of whether they are Bronze, Gold, Modular, Not-modular, etc. Every PSU currently available in the US that is less costly than this Core Reactor II unit is VERY questionable in terms of internal build quality and performance and since it's the singularly most important component in the build, it makes absolutely no sense to skimp here. In fact, I'd probably do this PSU BEFORE doing the memory if you can't do both at once. It might even self correct the problems without having to get other memory, but it also likely won't.
I believe doing these two things will cure your problem and if you can return your current PSU that would be wise. If not, maybe use it as a doorstop. Because that's literally what it's worth using it for. I wouldn't use a Masterwatt Lite even with a basic office machine with integrated graphics, or to power a light bulb for that matter.

The A550BN and A650BN units are "acceptable", barely, but considering they are like only twenty bucks less than one of the best PSUs you can buy at or near these prices, it makes literally zero sense since they have very poor internal component selection and likely won't last very long. Spend money on a good PSU, ONCE, and never worry about it again for like 7-10 years.

PCPartPicker Part List

Memory: G.Skill Ripjaws V 32 GB (2 x 16 GB) DDR4-3600 CL18 Memory ($54.99 @ Newegg)
Power Supply: ADATA XPG Core Reactor II 650 W 80+ Gold Certified Fully Modular ATX Power Supply ($79.98 @ Amazon)
Total: $134.97
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2025-05-31 13:26 EDT-0400

 

[Scallywags]

Thanks guys, Core Reactor II PSU on order. That's a smoking price for a full modular PSU! My biggest take away here is that my PSU is garbage and needs to get swapped out for a variety of reasons that have nothing to do with performance or RAM XMP profiles even if that does wind up helping to resolve the issue.

The RAM was purchased (also used) when I was just liberating the Ryzen 5 3500 and 1650 super from an HP prebuilt for my kids to play a popular FPS game who's name translates into "2 weeks" (for some reason I'm not allowed to post the actual name of the game).

Anyway, I might hold off on RAM and just run at base clock as long the games are running 100+ fps at 1080 then the kiddos should be pretty darn happy with this rig. It's a heck of a lot better than the 386 I grew up on! Anyone else miss the sound of a dot matrix printer???

 

[Darkbreeze]

Yes. But only because when I heard it printing I knew I was about to get paid on the invoice I was printing for a customer. (Early years as an auto shop owner.)

And at that time, which was very early 90's, I had just a 486sx system and the only thing worth really playing on it back then was Fuji golf. LOL.

 

[Misgar]

Also, the memory you have, Corsair LPX is WELL KNOWN to NOT "play nice" with Ryzen chipsets/CPUs.

Back in 2019, before I learned of potential problems matching LPX with Ryzens, I installed 2 x 16GB Corsair Vengeance LPX CMK32GXM2D3000C16 with a 3800X. The PC booted fine and I ended up with a stable 3000MT/s overclock after multiple runs in MemTest86.

A year later I took a chance and added another pair of LPX DIMMs with the same part number. I knew 4 DIMMs might be less stable than 2 and the two pairs would not be matched, but what the heck. Running Thaiphoon Burner I discovered both pairs use the same memory chips, but obviously from different batches.

After upgrading, I ran the four LPX DIMMs at JEDEC default speed. When I returned to a 3000MT/s overclock, they tested fine with MemTest86. The 3800X is still running well with 4 LPX at 3000MT/s to this day.

I'm not suggesting people should use LPX with Ryzens (I switched to 2x32GB Kingston DDR5 on the 7950X) but sometimes LPX is OK.

enabled XMP and adjusted the voltage in increments from 1.2 to 1.3 but it failed to post every time.

I've just checked the spec for my 16GB LPX DDR4 on the Corsair web site and the XMP voltage is 1.35V, not 1.30V as you tried. Perhaps the extra 50mV (0.05V) might work? I have seen people exceed this voltage and try 1.40V+ for silly XMP speeds, but I wouldn't recommend it.

I believe many mobo BIOS automatically boost the DDR4 voltage from 1.20V to 1.35V when XMP/EXPO/DOCP is enabled by the user.

My 3800X is running on a mobo with an X570 chipset and I might have stronger VRMs than your B450M. PSU is a Corsair RM750x on my 3800X and RM850x on the 7950x.

 

[Darkbreeze]

Right. I agree. The thing is, it's not that it CAN'T work, or WON'T work, it's that OFTEN it DOESN'T work, and so that is always the concern. And, more importantly, just because it DOES work with a specific Ryzen configuration does NOT mean it will work in that system when the cpu or motherboard has been changed. That is, simply, the way it is. Many have disagreed but then found it to be true. Shrug.

 

[Misgar]

I've lost count of the number of times I've made poor (or bad) choices when building a new PC (80386 onwards). Nothing catastrophic, but I sometimes wish I'd made better choices. That's why I started to read Tom's forums a few years ago, to glean useful tips and learn from other peoples' experiences.

I doubt I'll ever use LPX again in a new Ryzen system, but in the past, there wasn't always a huge choice of (affordable) RAM in on-line stores. So many things I'd like to buy on Amazon are "out of stock" and there aren't any local PC stores near me. My "excuse" is that DDR4 LPX was a good price back in 2019.