How do I power the third CPU slot on the MSI Z590 ACE Motherboard

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Jan 21, 2021
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My power supply (pictures included) only has two ports for CPU power. I know the last slot is not strictly necessary, but as I will be overclocking, I want to use it. Assuming I use the proper CPU power cord, can I use the VGA slot, or will that short-circuit my motherboard? I know this is a very specific question, so I've tried to make things clearer with pictures on the bottom.

Thanks in advance!

-Mitchell
 

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So the bottom slot is actually necessary? I thought it was only if we wanted to give the rig a little extra juice. And you're sure a VGA cable works? You booted yours up without problem?
 

MasterSaxGnz

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Not sure if it's optional but it is a PCI power. It is labeled as such in the manual. The VGA cables that plug into video cards are PCI power cables so they are the same just labeled differently. I attached page 8 of the manual.
 

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Nichrome

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Not required at all, unless you populate all PCIe slots with power hungry cards. Then such connector would provide bit extra power to reduce stress from board itself. For single GPU and some low power cards like M.2 adapters and sound card it is useless.
 

citay

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Nichrome explained it well. Normally, each installed card is allowed to draw up to 75W via its PCIe slot. Of course, a lot of graphics cards need way more than that, that's why they have seperate PCIe connectors. And actually, they tend to draw way more over the extra PCIe connector on the card than via the PCIe slot. Why do they do that? To not overwhelm the ATX power plug, because all PCIe slots are powered through the main 24pin ATX power plug. So let's say a graphics card needs 150 Watts total under load, then it might draw 120W via its 6pin PCIe connector and just 30W over the PCIe slot.

The graphics card makers already calculated with the 24pin ATX power having a limited amount of total wattage supplied to the board. So they make sure to draw most power over the seperate 6-pin or 8-pin connectors (or combination thereof) on the card itself.

Now, in the rare case that you have several quite "thirsty" cards in the PCIe slots, which disregard that consideration for the total 24pin ATX wattage and each draw the maximum allowed 75W each over their PCIe slot, then and only then would the PCIe 6-pin connector on the mainboard alleviate some of that high power demand from the 24pin ATX plug, and distribute it more evenly with the help of the second cable.

Similarly, for the two EPS12V connectors next to the CPU, the second connector is only there to spread the load, so to speak. When you have well over 300W power consumption of the CPU, which can only happen during OC, the second EPS12V plug comes in handy. You basically double the width of the cable and reduce resistance and load on each cable and plug, so they get less hot. On the mainboard itself, the connectors are combined again and feed the CPU VRM.

Lastly: Depending on which CPU you got, CPU overclocking is pretty much out of the question with Rocket Lake. Due to the four different, very aggressive turbo modes of the top-end CPU models, those CPUs are driven to 99% of their capabilities once you remove the power limits and give the turbo modes free reign. For the last 1%, you will have to live with an exponential increase in power draw and heat production, which can quickly overwhelm some of the best CPU cooling available.

Intel went right to the edge, especially with the 11900K. They went above the normal efficiency range of that silicon for this halo product, so it behaves - at stock, with power limits removed - like a substantially overclocked CPU would have behaved in the past. Meaning, the power draw is very high already, and the efficiency is quite low. If you still try to go above that with OC, you will see that the performance will hardly scale anymore, but the power draw and heat from the additional voltage required will rise incredibly steeply.

What's more, even RAM OC is largely limited to DDR4-3600. I've been extensively testing my own new Rocket Lake system this week, and i can tell you that DDR4-3600 is the new sweet spot. Because above it, you are forced to enter Gear 2 mode, where the memory controller runs with half the frequency of the RAM, which causes a serious performance loss. So you have to go way above DDR4-4000 to make up for that, which just isn't worth it. Just like on AMD, it's now best to stick to 3600 and optimize the timings.

Just so you can't say you haven't been warned ;)
 
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Nichrome explained it well. Normally, each installed card is allowed to draw up to 75W via its PCIe slot. Of course, a lot of graphics cards need way more than that, that's why they have seperate PCIe connectors. And actually, they tend to draw way more over the extra PCIe connector on the card than via the PCIe slot. Why do they do that? To not overwhelm the ATX power plug, because all PCIe slots are powered through the main 24pin ATX power plug. So let's say a graphics card needs 150 Watts total under load, then it might draw 120W via its 6pin PCIe connector and just 30W over the PCIe slot.

The graphics card makers already calculated with the 24pin ATX power having a limited amount of total wattage supplied to the board. So they make sure to draw most power over the seperate 6-pin or 8-pin connectors (or combination thereof) on the card itself.

Now, in the rare case that you have several quite "thirsty" cards in the PCIe slots, which disregard that consideration for the total 24pin ATX wattage and each draw the maximum allowed 75W each over their PCIe slot, then and only then would the PCIe 6-pin connector on the mainboard alleviate some of that high power demand from the 24pin ATX plug, and distribute it more evenly with the help of the second cable.

Similarly, for the two EPS12V connectors next to the CPU, the second connector is only there to spread the load, so to speak. When you have well over 300W power consumption of the CPU, which can only happen during OC, the second EPS12V plug comes in handy. You basically double the width of the cable and reduce resistance and load on each cable and plug, so they get less hot. On the mainboard itself, the connectors are combined again and feed the CPU VRM.

Lastly: Depending on which CPU you got, CPU overclocking is pretty much out of the question with Rocket Lake. Due to the four different, very aggressive turbo modes of the top-end CPU models, those CPUs are driven to 99% of their capabilities once you remove the power limits and give the turbo modes free reign. For the last 1%, you will have to live with an exponential increase in power draw and heat production, which can quickly overwhelm some of the best CPU cooling available.

Intel went right to the edge, especially with the 11900K. They went above the normal efficiency range of that silicon for this halo product, so it behaves - at stock, with power limits removed - like a substantially overclocked CPU would have behaved in the past. Meaning, the power draw is very high already, and the efficiency is quite low. If you still try to go above that with OC, you will see that the performance will hardly scale anymore, but the power draw and heat from the additional voltage required will rise incredibly steeply.

What's more, even RAM OC is largely limited to DDR4-3600. I've been extensively testing my own new Rocket Lake system this week, and i can tell you that DDR4-3600 is the new sweet spot. Because above it, you are forced to enter Gear 2 mode, where the memory controller runs with half the frequency of the RAM, which causes a serious performance loss. So you have to go way above DDR4-4000 to make up for that, which just isn't worth it. Just like on AMD, it's now best to stick to 3600 and optimize the timings.

Just so you can't say you haven't been warned ;)
Great response! I actually do have an i9-11900k, so that's quite useful. Would you say Overclocking it is still not worth it given I have a quality AIO? I've been told before that it's very easy to overclock to 5.3Ghz.
 

Nichrome

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If you have additional connector in your PSU, then it's bit more optimal to have it connected and won't hurt. But it's not a must. I run 9900K overclocked with single 8pin CPU connector.
Both are really needed for extreme OC, or those incredibly power hungry CPUs.
 

citay

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Define "easy". The main problem is the exponentially rising power consumption, because the CPU goes beyond the limit of efficiency at stock already.

I've read many reviews of the 11900K and they all concluded that OC is pretty much poinless. Let me quote a few interesting observations:

"As always we tried to overclock the processor. It certainly is doable but we're not sure if it is desired; proper liquid cooling is a must with this processor series. We got the processor stable at 5200 MHz all-core. 5300 MHz would boot fine, however created too many stability issues. At that point, we'd pass 1.5 Volts on the CPU. The heat production is significant. Realistically I'd say, leave tweaking for what it is as the defaults of these processors are already really close towards these performance regions.

5100 MHz all core yields 380W power consumption (system / GPU inactive)
5200 MHz all core yields 410W power consumption (system / GPU inactive)"

"Rocket Lake-S requires plenty of juice at the MCE-optimised frequencies run for the benchmarks on the previous pages. Overclocking by running the highest all-core speed at a set 1.4V gave us a final frequency of 5.1GHz, which is lower than what the chip boosts to on fewer cores.
You may ask the question as to why bother? This all-core 5.1GHz speed is the same as the supposed frequency the chip runs at with Adaptive Boost Technology enabled, while CPU-only power consumption rises to around 300W and puts our impressive Noctua cooler under tremendous pressure. The differences are minor, insofar as manually overclocking guarantees the frequency is applied at all times, not just when ambient conditions are correct.

Running all-core this way, the low-load PiFast result is actually slower.
Multi-thread benchmarks show a small gain in performance, intimating it's not really worth overclocking as one increases the chances of failure without a decent reduction in rendering time."

"The real jaw-dropper comes when you enable Adaptive Boost and watch the all-core speed push to 5.0GHz or 5.1GHz. The bad news is the five or six percent increase in clock speed requires 25 percent more power. These figures suggest that Intel has felt obliged to push way beyond the point of efficiency in a desperate scramble for clock speed and performance."

"Overclocking was really a tough nut on the Core i9-11900K. While I could boot at 5.1 GHz, it never was stable, not even with 1.5 V. So I settled for 5 GHz, which was easy enough, with just 1.4 V.

Unfortunately, this means that there really is no point to manual overclocking. Just increasing the power limit will yield you better performance while offering perfect stability. Also, Adaptive Boost can work on top of that."

"Turning on Adaptive Boost increases the CPU Package Power by a whopping 28%. Now, we in no way shape, or form saw a 28% uplift in performance. Therefore the power demand for the small percentage in performance we got across the board in our benchmarks is completely and wholly inefficient, and just quite insane to be honest."


Conclusion: Not worth it. ABT (Adaptive Boost Technology) is basically doing the overclocking for you, with already only little gains for a lot more power consumption. You won't get far beyond that. So just remove the power limits in the BIOS, enable ABT if you want, and hope that your cooling can handle it.
 
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Define "easy". The main problem is the exponentially rising power consumption, because the CPU goes beyond the limit of efficiency at stock already.

I've read many reviews of the 11900K and they all concluded that OC is pretty much poinless. Let me quote a few interesting observations:

"As always we tried to overclock the processor. It certainly is doable but we're not sure if it is desired; proper liquid cooling is a must with this processor series. We got the processor stable at 5200 MHz all-core. 5300 MHz would boot fine, however created too many stability issues. At that point, we'd pass 1.5 Volts on the CPU. The heat production is significant. Realistically I'd say, leave tweaking for what it is as the defaults of these processors are already really close towards these performance regions.

5100 MHz all core yields 380W power consumption (system / GPU inactive)
5200 MHz all core yields 410W power consumption (system / GPU inactive)"

"Rocket Lake-S requires plenty of juice at the MCE-optimised frequencies run for the benchmarks on the previous pages. Overclocking by running the highest all-core speed at a set 1.4V gave us a final frequency of 5.1GHz, which is lower than what the chip boosts to on fewer cores.
You may ask the question as to why bother? This all-core 5.1GHz speed is the same as the supposed frequency the chip runs at with Adaptive Boost Technology enabled, while CPU-only power consumption rises to around 300W and puts our impressive Noctua cooler under tremendous pressure. The differences are minor, insofar as manually overclocking guarantees the frequency is applied at all times, not just when ambient conditions are correct.

Running all-core this way, the low-load PiFast result is actually slower.
Multi-thread benchmarks show a small gain in performance, intimating it's not really worth overclocking as one increases the chances of failure without a decent reduction in rendering time."

"The real jaw-dropper comes when you enable Adaptive Boost and watch the all-core speed push to 5.0GHz or 5.1GHz. The bad news is the five or six percent increase in clock speed requires 25 percent more power. These figures suggest that Intel has felt obliged to push way beyond the point of efficiency in a desperate scramble for clock speed and performance."

"Overclocking was really a tough nut on the Core i9-11900K. While I could boot at 5.1 GHz, it never was stable, not even with 1.5 V. So I settled for 5 GHz, which was easy enough, with just 1.4 V.

Unfortunately, this means that there really is no point to manual overclocking. Just increasing the power limit will yield you better performance while offering perfect stability. Also, Adaptive Boost can work on top of that."

"Turning on Adaptive Boost increases the CPU Package Power by a whopping 28%. Now, we in no way shape, or form saw a 28% uplift in performance. Therefore the power demand for the small percentage in performance we got across the board in our benchmarks is completely and wholly inefficient, and just quite insane to be honest."


Conclusion: Not worth it. ABT (Adaptive Boost Technology) is basically doing the overclocking for you, with already only little gains for a lot more power consumption. You won't get far beyond that. So just remove the power limits in the BIOS, enable ABT if you want, and hope that your cooling can handle it.
Fair, yeah, I was only really thinking about ABT because of my nice cooling system, but honestly, I think I can probably shred anything as is and at the kind of fps I'll be getting when it's all configured, I don't think it's worth it to chew through the life of my CPU.

Thanks for the very thoughtful/insightful posts!

-M
 
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Fair, yeah, I was only really thinking about ABT because of my nice cooling system, but honestly, I think I can probably shred anything as is and at the kind of fps I'll be getting when it's all configured, I don't think it's worth it to chew through the life of my CPU.

Thanks for the very thoughtful/insightful posts!

-M
When I received my Godlike I was like WTF? This was mainly due to having only used ASUS boards for twenty years (my last MSI board had a Pentium4), jumping to MSI from a Z490 Maximus Hero was a head scratcher mainly due to different terminology and BIOS layout.

But when I got my head round it I love what you can do with a MSI BIOS with regards to level of freedom, I just find parts of BIOS overcomplicated or maybe I'm still adjusting.

Taken me about a week in total to get my 10900K stable at 1.25V with 0AVX offset but I got there, it's stable no matter type of load and does not go above 70 Degrees after four hours straight on CineBench and overnight on Prime.

I can get 5.2GHz on eight core plus 5.3GHz on two cores but this requires 1.42V for stability but temps jump considerably to 92 Degrees on full AVX load.

I'd just play with the board and get to know all settings and make the magic happen.

Enjoy
 

citay

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But there is no magic left to make happen, especially with the 11900K, but also already with the 10900K. 5.1 GHz is just 200 MHz over stock. That's almost nothing.

You see that these CPUs quickly reach a point where no additional VCore can push them further, without thermal throttling or becoming unstable. Already, if you notice the power consumption jumping up considerably for a minor OC, this is the CPU shouting "enough". Plus, if you start overclocking, you can cancel out the intelligent power management and the granular turbo modes.

Not to diminish your efforts, but that's a week's worth of work for nothing much to show, i suspect, if you compare your performance numbers before and after. You can only reach lower single-digit performance improvements, because the heat production gets out of hand quickly. I've talked about it with the 10900K here before: https://forum-en.msi.com/index.php?threads/over-voltage-on-msi-z490-gaming-plus.345590/#post-2000175

The last good Intel CPU for OC was the Core i7-8700K. The 9900K was a bit of a beast already. The 10900K and now 11900K, there are some faint remnants of OC, for those who want to do it no matter what. But the heyday of OC is over, both with AMD and with Intel. They both cannot afford to leave any unused performance anymore.
 
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I have now installed my motherboard. Has anyone been able to get it to work without using this power slot? I have nothing plugged into PCIE_1 and, if I'm in legacy BIOS, I'm getting error 62, "Installation of the PCH Runtime Services". If I'm in UEFI, which my old drives were configured to, I just get endless BIOS and it won't boot into anything. Wondering if these two things are connected. Due to tight cable management, it's actually really hard to plug this cable in at this point. Hoping I don't have to and that others got it to work without it.
 

citay

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It has nothing to do with that. The PCIe power on the bottom of the board will additionally supply power to the PCIe slots, should very PCIe-slot-power-hungry devices warrant it. With all the normal graphics cards you can buy, they get more than enough juice over the PCIe slot from the normal ATX plug.
 
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It has nothing to do with that. The PCIe power on the bottom of the board will additionally supply power to the PCIe slots, should very PCIe-slot-power-hungry devices warrant it. With all the normal graphics cards you can buy, they get more than enough juice over the PCIe slot from the normal ATX plug.
You're right. Nothing to do with it whatsoever. I know because I plugged the thing in and I still have the same problem. Lol.
 
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