Am I understanding the 290/290x load TDP correctly?

[Medwynd]

http://anandtech.com/show/7481/the-amd-radeon-r9-290-review/15

I have been putting some parts together over the past few months prepping for a new build come black Friday. I had purchased a Corsair HX850 assuming it would be enough power to drive 2 cards in either xfire or SLI, depending on how the new cards turn out.

Looking at the review posted today on the 290, it looks like the tdp at load is 375-381. I was hoping to do an minor oc on whichever cards I end up getting and also on the I7 4770K I planned on getting but it seems like I would be drawing way too much power for the HX850.

Am I going to need to step up to the HX1050 or in real usage outside of benchmarks will I be ok with an 850?

 

[Stuka87]

Anandtech does system load, they do not measure individual card load.

The card is a 300W card. So two fully loaded cards in stock form can draw up to 600W's. Now in theory it could draw over that when over clocked.

But realistically when gaming, the cards never draw 100% power 100% of the time. They jump around. If you run with VSYNC, then they can draw much less than max.

An 850W supply that delivers a TRUE 850W should be enough assuming you are using an intel CPU like you state

 

[smackababy]

They are measuring the entire system, not just the 290. And, I believe they can only measure draw from the wall.

You should be okay with an 850, I believe. A massive OC might put you in the danger zone though.

 

[96Firebird]

Anandtech's review uses the total system consumption.

I'm guessing 850W should be enough for 2 cards, but it also depends on how many HDD/fans/etc...

Edit - Beat 2x!

 

[Erenhardt]

That is whole platform power consumption.
There is 290 crossfire review at guru3d:
http://www.guru3d.com/articles_pages/radeon_r9_290_crossfire_review_benchmarks,4.html
Whole platform in full GPU load took 603Watts, that is Intel Core i7-3960X overclocked @4,6Ghz.

850 Should be enough IMHO.

 

[Aithos]

I know that they tend to do overall system, but 850 is still not leaving yourself much headroom for future system upgrades. I buy my PSUs to put into at least 2 builds so when I get mine I'll be going with a AX1200i no question. I want to overclock my CPU and both of my GPUs and having 80+ platinum is important for me.

Edit: Don't forget that less efficient power supplies don't deliver 100% of their rating, so once you start talking about load power consumption nearing the max your PSU is rated for you aren't going to have enough power. A more powerful PSU doesn't use more power from the wall, it means you have more headroom, the efficiency is the rating that matters most when you're getting close. That PSU isn't an 80+ platinum, so I would think it's not enough for an overclocked 4770k + 2x AMD GPUs.

 

[realibrad]

I know that they tend to do overall system, but 850 is still not leaving yourself much headroom for future system upgrades. I buy my PSUs to put into at least 2 builds so when I get mine I'll be going with a AX1200i no question. I want to overclock my CPU and both of my GPUs and having 80+ platinum is important for me.

@ OP

Do not factor this comment into your choice. 600w is far less than 80% of the 850W power supply. There is no need to pay more for a higher watt PS. If you find one of the same quality that is more watts, fine, but dont feel the need to go for something higher.

 

[Medwynd]

Thanks guys, I knew I was missing something obvious

 

[Lonyo]

Also power from the wall is not the same as the load on the PSU.
Even if you assume 90% efficiency (platinum I think?), your 600w load is actually only 540w on the PSU, and then 10% lost in inefficiencies.
That's 63% load.

 

[Aithos]

@ OP

Do not factor this comment into your choice. 600w is far less than 80% of the 850W power supply. There is no need to pay more for a higher watt PS. If you find one of the same quality that is more watts, fine, but dont feel the need to go for something higher.

OP - please have a look at some wattage calculators before you make your decision. These guys are underestimating the total power draw of a CF system with one of the most power hungry cards currently on the market. You're talking about overclocking a CPU and two GPUs on top of the other power requirements for the system. Without knowing how many SSDs/HDDs you're running, how many fans, etc, it's hard to say. But have a look at this:

http://www.realhardtechx.com/index_archivos/Page362.htm

and figure out your system here:

http://extreme.outervision.com/PSUEngine

I put in a 4.2ghz OC 4770, 2x 290x (they don't have the 290 in there, same TDP) and a basic config with a bluray drive, 5 fans (2 140 front, 1 140 back and 2 120 either cpu or rad) with a ssd and an hdd and even without the OC on the GPUs it comes up with 800w for 90% load and 890 watts for 100% load.

If you think a top end CPU w/OC and two top end GPUs w/OC is ok on 850 watts...go ahead. I wouldn't do it, whats an extra $100 when you're talking about close to $1000 for your GPUs anyway?

Edit: 80% of 850 is 640w. I'm sorry, but if you think that's enough to run all those overclocks, the MB for an overclocked system, all the fans, controllers and drives with any kind of load you are crazy. If you want some completely subjective opinion, here it is: If 850 was "easily" enough, reviewers wouldn't bench with 1200w PSUs to take it out of the equation. Even in the review on this site the total draw of a 4.2 system was 727 with 2x 290x and that was without OCing the cards and a mild overclock on the CPU.

 

[smackababy]

The 290x is a 300w card so that is 600w + an 84w CPU (and if we double it for OC) that still leave us below 800w. And, you will almost never be pushing 100% power in an situation where you weren't actively trying to push 100%. Plus, reviews are showing a CF system in synthetic benchmarks pulling under 700w from the wall. With 90% efficiency, you're looking at less than 650w system total. A quality 850w will do just fine.

 

[Lonyo]

OP - please have a look at some wattage calculators before you make your decision. These guys are underestimating the total power draw of a CF system with one of the most power hungry cards currently on the market. You're talking about overclocking a CPU and two GPUs on top of the other power requirements for the system. Without knowing how many SSDs/HDDs you're running, how many fans, etc, it's hard to say. But have a look at this:

http://www.realhardtechx.com/index_archivos/Page362.htm

and figure out your system here:

http://extreme.outervision.com/PSUEngine

I put in a 4.2ghz OC 4770, 2x 290x (they don't have the 290 in there, same TDP) and a basic config with a bluray drive, 5 fans (2 140 front, 1 140 back and 2 120 either cpu or rad) with a ssd and an hdd and even without the OC on the GPUs it comes up with 800w for 90% load and 890 watts for 100% load.

If you think a top end CPU w/OC and two top end GPUs w/OC is ok on 850 watts...go ahead. I wouldn't do it, whats an extra $100 when you're talking about close to $1000 for your GPUs anyway?

Edit: 80% of 850 is 640w. I'm sorry, but if you think that's enough to run all those overclocks, the MB for an overclocked system, all the fans, controllers and drives with any kind of load you are crazy. If you want some completely subjective opinion, here it is: If 850 was "easily" enough, reviewers wouldn't bench with 1200w PSUs to take it out of the equation. Even in the review on this site the total draw of a 4.2 system was 727 with 2x 290x and that was without OCing the cards and a mild overclock on the CPU.

The PSU calculators over-estimate.
There is a built in level of overage.

For one of my builds, it recommends a 257w PSU, with a 211w minimum.
I run it on a 220w PSU, and it draws around 120w peak from the wall.

For what's in my signature, it recommends 350w, min 305w.
I have not seen above 250w from the wall.

If it says 850w recommended, the actual system load will probably be 80% of that from the wall, and then take 90% of THAT for actual PSU load.
That means you would be 72% loading an 800w PSU at most, which puts us back where we started at around 600w, like Guru3D shows with its benchmarks using an OVERCLOCKED CPU.

And the OP said minor overclock, not a big one.

PSU calculators already build in a margin of safety, even on their minimum recommendation, the recommended recommendation has even more safety.

 

[Phynaz]

OP - please have a look at some wattage calculators before you make your decision.

Online wattage calculators are bunk.

Your linked calculator says the minimum PSU for my system is 300 watts, with 350 recommended.

With a max load power virus (Furmark and IBT) my system draws under 250.

 

[Stuka87]

Online wattage calculators are bunk.

Your linked calculator says the minimum PSU for my system is 300 watts, with 350 recommended.

With a max load power virus (Furmark and IBT) my system draws under 250.

You have to of entered something wrong.

For my system (in sig) it shows 488W peak. I have personally measured just over 480W with CPU and GPU loaded. So I would say it is pretty darn close.

 

[Medwynd]

If you think a top end CPU w/OC and two top end GPUs w/OC is ok on 850 watts...go ahead. I wouldn't do it, whats an extra $100 when you're talking about close to $1000 for your GPUs anyway?

Agreed, but I already have the PSU I was looking to evaluate my options in case I should need a larger one which means I would have to sell off my current unused 850 which would be a pain.

 

[chimaxi83]

I don't think 850 is enough to be comfortable.

I did a quick run at stock clock but with 1.3V (to simulate somewhat typical overclock voltage), using a separate PSU for 8+6 power. Measuring just the card, I was hitting nearly 400 watts. Accounting for PSU efficiency, that's ~340 watts. Add the 75 watts from the PCIE slot, and you can see the potential power draw.

https://www.youtube.com/watch?v=aG_KlGQb3I4&feature=youtube_gdata_player

 

[Medwynd]

I don't think 850 is enough to be comfortable.

I did a quick run at stock clock but with 1.3V (to simulate somewhat typical overclock voltage), using a separate PSU for 8+6 power. Measuring just the card, I was hitting nearly 400 watts. Accounting for PSU efficiency, that's ~340 watts. Add the 75 watts from the PCIE slot, and you can see the potential power draw.

https://www.youtube.com/watch?v=aG_KlGQb3I4&feature=youtube_gdata_player

Hmm, I don't really want the headache of selling of this PSU so it looks like my options are to not OC the cards and/or the chip, to possibly try GTX 780s since they seem to draw less power, or wait and see what the 780ti cards do.

That's what I get for trying to get parts on sale

EDIT: I guess I should note that I will be playing at 2560x1600 which is why I was leaning towards the 290X with its 4GB of VRAM

 

[chimaxi83]

Hmm, I don't really want the headache of selling of this PSU so it looks like my options are to not OC the cards and/or the chip, to possibly try GTX 780s since they seem to draw less power, or wait and see what the 780ti cards do.

That's what I get for trying to get parts on sale

EDIT: I guess I should note that I will be playing at 2560x1600 which is why I was leaning towards the 290X with its 4GB of VRAM

I don't think 780s will give you any issues with "only" 3GB VRAM

 

[YBS1]

FWIW....I was shutting down a 1300watt psu during 3DMark runs. Granted a 5.1GHz 3930K is a true power hog and my 780's are running a custom bios. You can't "overbuy" on a psu.

 

[OVerLoRDI]

Btw. Anandtech uses system load

 

[BrightCandle]

Actually you can "overbuy" a PSU. The problem is they are designed to run between particular loads, typically 20-80%. You need to get your idle and load consumption in the efficient part of the PSU's curve or your electricity bill will be a lot higher than it needs to be. Not to mention the fact it costs more money and brings literally zero benefit to the machine.

I suspect the OP doesn't even remotely need an 850W PSU, that is probably far more than is needed for one of these cards and the rest of the machine. It will more than do the job, it will probably waste more power than it needs to.

 

[YBS1]

Context man, context. If he's going to be running two 290/780's he will be inside the meaty part of the efficiency curve even with a monster psu. An 850 watt psu may very well be enough for him depending upon how hard he pushes the cards and cpu, but it's certainly not going to have a lot of headroom. You also never know what you may do in the future, I'd rather buy a little more now than "just enough" each time I made a change.

 

[Medwynd]

Context man, context. If he's going to be running two 290/780's he will be inside the meaty part of the efficiency curve even with a monster psu. An 850 watt psu may very well be enough for him depending upon how hard he pushes the cards and cpu, but it's certainly not going to have a lot of headroom. You also never know what you may do in the future, I'd rather buy a little more now than "just enough" each time I made a change.

So I did a calculation with the extreme power supply calculator online and landed at minimum 778W recommended 828W without any OC.

This included:
I7-4770K
2 x R290X
1 7200 RPM HD
1 SSD HD
1 BluRay drive
1 PCI-E x1 card for my Creative Sound Blaster Zx
Corsair H100 w/ 4 120mm fans
Then a bunch of fans for my HAF-X case which was 3 x 200mm, 1 x 140mm, 1 x 230mm fans

The same setup with 2 x 780Ti ended up with min 687W recommended 737W

 

[MrK6]

290/290X's seem to be high leakage chips. An 850W PSU is more than enough for stock operation as many have said. The caveat I'd leave is that because they are high leakage, power draw will scale immensely once you start overclocking. If you really want to take these cards far (1200MHz+ with voltage to match), your system will easily exceed 850W, as chimaxi83 pointed out.

 

[MeldarthX]

Hmm, I don't really want the headache of selling of this PSU so it looks like my options are to not OC the cards and/or the chip, to possibly try GTX 780s since they seem to draw less power, or wait and see what the 780ti cards do.

That's what I get for trying to get parts on sale

EDIT: I guess I should note that I will be playing at 2560x1600 which is why I was leaning towards the 290X with its 4GB of VRAM

Gibbo who has crossfired has stated 850 for two is more than enough; but if you want to go more......you will need bigger; specially if you want to max OC; for normal you got space....specially with a quality psu.....the higher the number does not always = better....its the quality of amp and volts on the rails that counts.