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  1. #1

    Power Supply Needed for OC 9900k + 3090 FE

    Hey folks,

    1)I was fortunate to nab a 3090 FE via Best Buy today and I'm curious if my power supply is up to the task. The 3090 FE will be partnered with a 9900k that's OCd to 5ghz on all cores + a Corsair a500 air cooler. Right now my rig is powered by a Corsair RMx (2018) 750 W 80+ Gold Certified Fully Modular ATX Power Supply. I understand the 3090s are beasts for power, do you think a new supply is needed to keep up?

    2)Would a processor and MB upgrade also be beneficial? I can easily nab a 10900k but unsure if the performance gains would be beneficial with the 3090.

    Thanks in advance.

    EDIT: After doing some research, I believe the answer is a resounding yes. But there's a debate between 1000 and 1200 that I would hope to get some feedback on
    Last edited by Erous; 2021-01-05 at 07:42 PM.

  2. #2
    I don't know what kinda power a OC 9900K draws but isn't the 3090 like 300/350 W?

    I'd say an 800-850 80 + Gold or better from a reputable manufacturer like Seasonic, Be Quiet, Corsair, Gigabyte etc.


    2)Would a processor and MB upgrade also be beneficial? I can easily nab a 10900k but unsure if the performance gains would be beneficial with the 3090.
    If you upgrade to a 10900k you will need a motherboard upgrade too.

    The 9900k and 10900k are different socket types.



    The 9900k is an LGA 1151 CPU that runs on the Z390 Chipset.

    The 10900k is an LGA 1200 CPU that runs on the Z490 Chipset.
    Last edited by AntenoraDK; 2021-01-05 at 10:28 PM.

  3. #3
    Quote Originally Posted by AntenoraDK View Post

    If you upgrade to a 10900k you will need a motherboard upgrade too.

    The 9900k and 10900k are different socket types.

    The 9900k is an LGA 1151 CPU that runs on the Z390 Chipset.

    The 10900k is an LGA 1200 CPU that runs on the Z490 Chipset.
    Right, I understand that. My current machine would go to my son and I'd build new. I just wasn't sure if the move to 10900k would be worth it.

  4. #4
    Quote Originally Posted by Erous View Post
    Right, I understand that. My current machine would go to my son and I'd build new. I just wasn't sure if the move to 10900k would be worth it.
    No. the 9900K and 10900K are almost exactly the same chip. Performance would be within the margin of error.

    As for PSU... my 3080 has never drawn more than 300W, even when maxed out with Furmark. Now, i know that the 9900K heavily OCed can suck down some juice, but i cant imagine it being more than another 200-300W for the rest of the system (incl the CPU) even under synthetic load.

    The 3090 will likely draw mroe than a 3080 - lets say 400W - so.... 800+W should be fine.

  5. #5
    I took 850w for my old 1080ti. With new series, and I am not even kidding, taking 1250w or higher would totally be not over the edge.

    It's complicated to explain in detail and I'm not the best person for it either, but 850 or less might not be enough, esp. in a long run.

  6. #6
    Quote Originally Posted by ShinyInfidel View Post
    I took 850w for my old 1080ti. With new series, and I am not even kidding, taking 1250w or higher would totally be not over the edge.

    It's complicated to explain in detail and I'm not the best person for it either, but 850 or less might not be enough, esp. in a long run.
    1250 woah man let’s not get crazy here lol

    https://www.tomshardware.com/amp/new...-shortage-2020

  7. #7
    Quote Originally Posted by Synical123 View Post
    1250 woah man let’s not get crazy here lol

    https://www.tomshardware.com/amp/new...-shortage-2020
    Interesting, thanks for this and thanks to Kag and Shiny as well. Looks like I will need a new PSU because I need to bump to at least 850 gold as noted on the Toms Hardware chart there.

    I figured the boost between 10900 and 9900 would be negligible, so I appreciate the clarification there as well.

  8. #8
    Quote Originally Posted by ShinyInfidel View Post
    I took 850w for my old 1080ti. With new series, and I am not even kidding, taking 1250w or higher would totally be not over the edge.

    It's complicated to explain in detail and I'm not the best person for it either, but 850 or less might not be enough, esp. in a long run.
    Well being that you're like... wrong.. makes it hard to explain.

    1250W would be absolutely fucking insanity for a single GPU non-workstation system. Even heavily OCed Intel CPUs at 5+ghz aren't pulling more than 200W. A 3090 under full synthetic load will pull less than 400W, unless you buy one of the few 3rd party AIB cards that has a second BIOS with unlocked voltage limits (like the Kingpin cards) and overclock the bejezus out of it, and even then, unless you have exotic cooling, its not going to pull more than 550W. The card will just not let you.

    So back in the real world where we arent all using Kingpin cards, 400W for the GPU, 200W for the CPU (lets say 300W for the sake of overcommpensating) and another 100W for the entire remainder of the system (also shooting absurdly high)... we're at 800W.

    Yeah, having some headroom can be nice.. so a 900W PSU would be fine, but they arent really made in that wattage so youd have to go to 1000W.

    But 1250? Not in this world. And going forward, you can expect power consumption to continue going DOWN (as it has for the last 12 years) on average. nVidia will be refining Ampere into its next product which will use less power (just because itll be on a smaller node if nothing else, even if they just cop out with an Ampere+), as will AMD. CPUs have been falling this entire time. Only time they exceed ~125W is when you OC heavily multicore CPUs, which the average gamer is just not doing. Hell, the average anyone. OCing is done by single-digit percentages of the community.

  9. #9
    Quote Originally Posted by Kagthul View Post
    Yeah, having some headroom can be nice.. so a 900W PSU would be fine, but they arent really made in that wattage so youd have to go to 1000W.
    Thanks, that seems to match the Toms Hardware chart also. I was thinking that if the STOCK requirement for the 3090 and 9900k is 850, pushing an OC would test that number but because there's no 900w, 1k is the likely choice here.

  10. #10
    Quote Originally Posted by Erous View Post
    Thanks, that seems to match the Toms Hardware chart also. I was thinking that if the STOCK requirement for the 3090 and 9900k is 850, pushing an OC would test that number but because there's no 900w, 1k is the likely choice here.
    I was using the absurd numbers in my post that have no bearing on real life, and even then, 1000W is more than enough.

    For the real world 850 should be fine.

    The numbers that sites and the manufacturers (especially the manufacturers) throw out are Cover-your-ass numbers so they dont get sued.

    nVidia tells me i should have a 750W PSU minimum for a 3080... and yet i have an OCed one, and my entire system doesn't even pull 550W from the wall on a full on torture test (FurMark + Prime 95). Which aren't numbers you're ever going to hit in real life.

    And you can save a decent bit of wattage by undervolting, even if you are OCing. nVidia tends to gratuitously overvolt their chips by default to ensure that the few "less than amazing" chips dont have issues, but on my 3080 ive got it locked at .875v (down from 1.075-1.1v by default) and it still hits 1975mhz stable. Thats kep it well below 300W during real world gaming loads and in the 290W range even under torture test.

    Same with your CPU. You can OC and still undervolt in a lot of cases. My 8600K runs between 4.8Ghz-5ghz (i lower it during the summer because i dont run AC in my house and its HOT in here) and ive got it at 1.20v.

    But even if you dont want to fool with that - at stock voltages, your entire system, even OCed on the CPU you the way you have it, likely wouldn't pull more than 650W under torture loads. Maybe 700. There's little to no point in OCing the 3090 - nVidia's Thermal Velocity Boost will let the card boost as high as it can go anyway, within termal constraints.

    People often massievly overestimate how much PSU they need. The numbers given out on parts (like nVidia recommending 750W for a 3080) are just CYA for the average consumer who doesn't know better and likely has some sub par PSU. If you're remotely knnowledgeable about computers and have a quality PSU, you can do the math yourself and generally realize you dont need nearly what is suggested.

  11. #11
    https://outervision.com/power-supply-calculator

    It says 519w with 2 SATA SSDs. Then add up the amount of overclocking you want to do (The tdp of overclocked CPUs can go up quite a bit, 200-300w is not impossible). Also the GPU uses some kind of boost clock so a bit of leeway is recommended to remedy the chance of power starving your GPU.

    And then there is the efficiency factor where your PSU is more efficient when its not under maximum load all the time.

    I would recommend at least a 750w PSU if you plan on not overclocking anything and at least a 850w PSU if you plan on overclocking the CPU which is also recommended.

  12. #12
    You need a 850W unit. All power calculators are retarded btw, you dont ever build gaming system that will run at 70-80% of capacity under load.
    i7-6700K @ 4.6GHz cooled by Thermalright Silver Arrow IB-E Extreme | ASRock Fatal1ty Z170 Gaming K6+ | 16GB Corsair Vengeance LPX DDR4-3000/CL15 @ 3200/CL14 | MSI GTX 1070 Gaming X | Corsair RM650x | Cooler Master HAF X | Logitech G400s | DREVO Excalibur 84 | Kingston HyperX Cloud II / Samson SR850 | BenQ XL2411T + LG 24MK430H-B

  13. #13
    I went to a Corsair RM1000i for my 10900k and 3090 Build. Same thing for my 5950x and 3090.

  14. #14
    Quote Originally Posted by SigmaShift View Post
    I went to a Corsair RM1000i for my 10900k and 3090 Build. Same thing for my 5950x and 3090.
    Why?..... Those systems wont even use 850w
    Intel core i9 9900k: Gigabyte z390 Aorus Master: PNY RTX 2080 XLR8 OC Twin 8GB: CORSAIR HX850i: CORSAIR Dominator Platinum RGB 32GB 3200MHz: Samsung 960 EVO 250GB NVMe: fiio e10k: lian li pc-o11 dynamic: Acer Predator xb271hu: Custom water cooled

  15. #15
    Quote Originally Posted by pansertjald View Post
    Why?..... Those systems wont even use 850w
    Price difference is minimal between an 850 and 1000, and no, you're wrong, not when both devices are OC'd. You should never run a PSU near capacity.

  16. #16
    Quote Originally Posted by SigmaShift View Post
    Price difference is minimal between an 850 and 1000, and no, you're wrong, not when both devices are OC'd. You should never run a PSU near capacity.
    Your Intel system will at worse case run at about 750w and that is if you run your CPU at 5.3GHz and you oc your GPU as much as it can AND you need to have your system running at a 100% at all time to reach that and you will never run your system at a 100% at all time. Just gaming and other normal stuff, you will be using about 600w

    Your AMD system will run at worse case at about 600w.

    So a good 850w platinum PSU would have been more then enough for both systems
    Intel core i9 9900k: Gigabyte z390 Aorus Master: PNY RTX 2080 XLR8 OC Twin 8GB: CORSAIR HX850i: CORSAIR Dominator Platinum RGB 32GB 3200MHz: Samsung 960 EVO 250GB NVMe: fiio e10k: lian li pc-o11 dynamic: Acer Predator xb271hu: Custom water cooled

  17. #17
    Quote Originally Posted by pansertjald View Post
    Your Intel system will at worse case run at about 750w and that is if you run your CPU at 5.3GHz and you oc your GPU as much as it can AND you need to have your system running at a 100% at all time to reach that and you will never run your system at a 100% at all time. Just gaming and other normal stuff, you will be using about 600w

    Your AMD system will run at worse case at about 600w.

    So a good 850w platinum PSU would have been more then enough for both systems
    I'll stick with the 1000w for $20 more. There are also dual water loops in each system, and a plethora of fans and drives. I just tested the intel system and at peak its pulling 790w. Assumptions are terrible, aren't they? You should always leave 20% head room on a PSU.

    I'm questioning why you would try to recommend someone to risk a high dollar system over a few dollars saved in a smaller PSU... absolutely senseless.
    Last edited by SigmaShift; 2021-02-02 at 01:33 AM.

  18. #18
    Quote Originally Posted by SigmaShift View Post
    I'll stick with the 1000w for $20 more. There are also dual water loops in each system,
    So, 25W, tops, for each pump? Usually more like 15.

    and a plethora of fans
    5W each? Maybe?

    and drives.
    5-10W each at most for spinning rust. 5W or less for an SSD.

    I just tested the intel system and at peak its pulling 790w.
    790W from the wall on an 80+ gold means its supplying about 660W to the system. So, well below the 850W panser recommended (almost 200W). And thats full on FuMark + Prime95 torture load which is 100% unrealistic and will literally never occur in real usage.

    Assumptions are terrible, aren't they?
    Irony escapes you.

    You should always leave 20% head room on a PSU.
    Urban myth. Much like "dont swim for 30 minutes after you eat" and other nonsense. Its "common wisdom" that actually doesn't have any bearing on reality and is actually just not true. Seriously, go to a PSU centric forum (where you will see this thrown around all the time), and then ask they why. The answers will be "because". Because its not a real thing and no one actuallly knows. And then, rarely, an actual electrical engineer will chime in and debunk it.

    Now, do you want to run the thing at 100%? No. Of course not. But the 20% thing is a myth.

    Hell, if you're looking for best efficiency, they are best at ~85-90% capacity. Thats when the hit their highest efficiency numbers on their rating

    I'm questioning why you would try to recommend someone to risk a high dollar system over a few dollars saved in a smaller PSU... absolutely senseless.
    Because he wasn't suggesting that. (See above; what it pulls from the wall is NOT relevant to its capacity; the capacity number is what it can supply after it converts it to DC) Im not even sure you understand how PSUs work.

  19. #19
    Quote Originally Posted by SigmaShift View Post
    I'll stick with the 1000w for $20 more. There are also dual water loops in each system, and a plethora of fans and drives. I just tested the intel system and at peak its pulling 790w. Assumptions are terrible, aren't they? You should always leave 20% head room on a PSU.

    I'm questioning why you would try to recommend someone to risk a high dollar system over a few dollars saved in a smaller PSU... absolutely senseless.
    As Kagthul said. You have no idea of how a PSU works. Its really sad to see how many people that buys way to big PSUs for their systems. Steve from GN even mention it in one of he's PSU videos. And i didn't recommend you ANY thing at all. I just told you what you should have bought instead of.

    Your AMD system can run on a good 750w gold/platinum PSU without even hitting 600w 99% of the time
    Intel core i9 9900k: Gigabyte z390 Aorus Master: PNY RTX 2080 XLR8 OC Twin 8GB: CORSAIR HX850i: CORSAIR Dominator Platinum RGB 32GB 3200MHz: Samsung 960 EVO 250GB NVMe: fiio e10k: lian li pc-o11 dynamic: Acer Predator xb271hu: Custom water cooled

  20. #20
    Quote Originally Posted by pansertjald View Post
    Why?..... Those systems wont even use 850w
    You never want to run at 100% capacity and it can easily hit over 80% with those components and overclocking?

    - - - Updated - - -

    Quote Originally Posted by pansertjald View Post
    Your Intel system will at worse case run at about 750w and that is if you run your CPU at 5.3GHz and you oc your GPU as much as it can AND you need to have your system running at a 100% at all time to reach that and you will never run your system at a 100% at all time. Just gaming and other normal stuff, you will be using about 600w

    Your AMD system will run at worse case at about 600w.

    So a good 850w platinum PSU would have been more then enough for both systems
    Only if you want it running at near max capacity when under load... which nobody with half a brain would.

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