Is a Radeon 7870 going to run with a 240W PSU?

Zane24 · Mar 21, 2017

Here's the specs:

6th Generation Intel® Core™ i5-6500 Processor (Quad Core, 6MB, 4T, 3.2GHz, 65W)

8GB RAM (2x4GB)

500GB HDD

8x DVD+/-RW 9.5mm Optical Disk Drive

Windows 10 (64-bit)

Basically I'd like to know what PSU I should get if I want to add an AMD Radeon to this PC.

n0ns3ns3 · Mar 21, 2017

for the specified in title, something like 350 watt and more of good PSU

herrwizo · Mar 21, 2017

This GPU uses approximately 130W under full load, and that does not even account the other components in your PC. Do not even attempt to run that rig with a 240W PSU. 350W is also not enough, unless you wish to push the PSU to the maximum and make it die within a few days/weeks. You always need some healthy headroom for PSU longevity and stability.

Get a decent quality (and at least 450W) PSU from Seasonic, Antec, XFX, EVGA.

jdcranke07 · Mar 21, 2017

Zane24 :

A 350W is all you would need, but it isn't recommended at all. Since an equivalent system will only draw ~335W max. I personally would go with a 500W or 650W for head room to expand in the future and if you get a PSU that is good and has a higher wattage rating, it will stay cooler since it isn't having to work as hard. Assuming you wanted to push you system to best performance.

4745454b · Mar 21, 2017

The 7870 uses a lot more than 130W. The 7870 has two 6pin plugs. It's the 7850 that has only a single 6pin plug and a ~130W power draw. The 7870 is AMDs ~175W part. If you add the 65W for your CPU and my general 50W for the rest of the system you are looking at a load of around 290W. Well above what a 240W can output.

Assuming you don't want your PSU to output more then 80% of it's power, you need something that will output 362.5W (31A) on it's 12V rail. This is most 500W units and some 450W units. Make sure it's a quality unit and has the two 6pin plugs you need. I don't remember if there are 7870 models that need an 8pin, there are probably a few random ones out there that might.

Sakkura · Mar 21, 2017

4745454b :

Not really. You can push it closer to 150W in Furmark, but generally it peaks at about 125W in games. Techpowerup actually measured it peaking at 115W, with an average of 103W. Tom's measured the higher clocked R9 270X at 124W.

A 125W GPU with a 65W CPU and, say, 50W for the rest - meaning the system will likely never pull more than 240W. That's still too much on a 240W power supply. A 350W PSU should be sufficient, but there isn't much margin for error or room for upgrades or overclocking, and many 350W units are pretty crappy. It would probably be best to step up to a decent 430-450W unit. But that's way plenty.

4745454b · Mar 21, 2017

First, I used, as I always do, the stated TDP. It's easier to remember compared to all the different cards out there and it's usually the "worst case" unless you are looking at a Maxx, Top, etc card. When "playing" with other people's money I always err on the side of caution. Besides, you never know when X game comes out and bumps things up a notch and the previous "gaming max load" no longer applies.

You linked to a stock model, and a refresh model. Here is a review for an OC'd 7870.

http://www.kitguru.net/components/graphic-cards/zardon/gigabyte-hd7870-overclock-review-windforce-3x/19/

The gaming mode does indeed hit ~150W. But as I mentioned above you can't really plan on that because what happens when he runs X program and goes above that? What happens when X game comes out and demands more from the card? What happens if he starts mining with his 7870 and hits that 180W number? Using the stated TDP works out better in the long run.

A 350W PSU should be sufficient, but there isn't much margin for error or room for upgrades or overclocking, and many 350W units are pretty crappy. It would probably be best to step up to a decent 430-450W unit.

And again don't forget about the PCIe plug requirements. You need dual 6pin plugs for that card. (If it was a real 150W card you'd only need a single 6pin PCIe plug.) I think I've seen one 430W PSU with those plugs, and it's a very new gold rated unit. 380-430W units just don't have the plugs needed to run that card. Trust me, 450W minimum is what I'd consider, and the plugs found on PSUs would agree with me.

n0ns3ns3 · Mar 22, 2017

4745454b :

SRSLY ?
the PCIe 6pin can carry over 200watt (17A*12V) and 8pin is over 300watt (25.5A*12V) - that's molex spec.
the way that AiB vendors use those is in many cases the same as some car manufacturers use fancy exhaust system or spoilers - look we have many - we are powerful.
PCIe cards are limited at 300watt by PCIe spec. they can get up to 75watt directly from PCIe. wich leaves 225w to draw from PSU. So for ANY card in the world within specs, a single 8pin connector would be more than enough with huge headroom. a 6pin + PCIe = 280watt continuous power.
back to the case, even if the card is 200w peak draw part, and the rest of the system is 130watt, a GOOD 350w PSU would definitely enough for a 24/7 usage.

herrwizo · Mar 22, 2017

Molex spec is one thing, PSU design is another. The 8-pin connector is designed to supply up to 150W of power, the 6-pin up to 75W.

n0ns3nse, if you really feel so confident in your claims, then go ahead and recommend a certain 350W PSU model to the OP. I would not have a heart to do that, since it's his money and rig, not my own, to risk.

n0ns3ns3 · Mar 22, 2017

that's getting funny.
no PSU has 150w limit on 8pin. many have a single cable coming out of the PSU that on the other end serves as 2x(6+2)pin. this limitation is purely implemented in cards. it's even not HW limitation. it is set in BIOS. And has no connection to the cable/connector capabilities. Except of showoff/wow factor with placing many connectors on the card, the only practical reason is to distribute power delivery across more PCB lanes even in few layers. that keeps PCB cooler, allows less copper (the electricity use a surface of conductor and not going in due to resistance).
I do not insist on 350, I just say it's the recommended minimum.
here is an example of 300w decent quality unit that is capable of delivering 25A of 12V in continuous load = 274w is fine for most systems. OP's system is not an exception.

4745454b · Mar 22, 2017

You forgot the link.

Again, when dealing with other peoples systems and money, I go by the spec. 75W for a 6pin, 150W for an 8 pin. If YOU want to be reckless and push something to the limit go for it. Come back every year and tell us how it's going. I know of some of the mods here who use less then good named PSUs and they do work. But when it comes to suggesting parts that we trust we don't suggest the lesser brands.

There are no 300W ATX PSUs that I know of that have the plugs needed to run that card. Period. There are no 380W PSUs that have the plugs needed to run that card. I've seen one 430, and there are many 450Ws that can do it. Why suggest a 300 or 350 if the OP goes out and buys it only to find out he can't plug the card in? Way to help him out there.

I'd also point out load/efficiency. 274/300= 91.3% load. Dear Lord are you serious? While I like it when the sites load a PSU up to 100% or even 110% so I can make sure it can deliver it's rated power at such extremes, I'd never run a PSU at the edge like that. 75-80% is the max I'd go. This means something that can output 342.5 on the 12V rail, or around 29A. And as long as it has the plugs needed to run the card he should be good with such a PSU.

Saga Lout · Mar 22, 2017

If you don't already own a 240 Watt PSU, why ask the question. If you do have one, donate it to the nearest antique shop and but a decent PSU.

n0ns3ns3 · Mar 22, 2017

@Saga, some OEM computers (Dell, HP, Lenovo etc.) come with under 300w PSU since they are not designed for dGPU.

@4745454b,
here is the link, it comes with 6pin which can be duplicated or/and converted to 8pin http://www.silverstonetek.com/product.php?pid=458
We are not arguing about what OP should get, decent low power (400 and less) PSUs are still rare and only recently started to show up. They are not cheap.
They are capable of powering system with i5 and sub 200w card for daily usage since gaming power draw of such system would be in 200-250w range from the WALL.
That does not mean that OP should get such unit. Most probably, it would be much more practical to get 450-550ц unit.

And we are not discussing our personal preferences. Mine is to have PSU in 0 RPM mode most of the time -> ~40% load. inefficient but silent.

To end this argument, my recommendation in the first post "350w and MORE of a good PSU". Which is still in place. If and when OP will ask for a PSU recommendation, we will need more info, like computer case for space restrictions, budget, OP's location/favorite store etc. For a theoretical discussion and the OP's question, it does provide a correct answer.

Saga Lout · Mar 22, 2017

n0ns3ns3 :

Many of which pass through my PC repairing business in England and it's been a while since I've seen one unless it was the long, slim ones to fit in miniature cases. I've never seen one with 6+2 or 8 pin to power an add-one graphics card.

Lutfij · Mar 22, 2017

That PSU wattage reminds me of an Optiplex unit by Dell. To answer your question, no that 240W unit will not be capable of powering the entire system+the 7870 GPU. Last I checked, those units are proprietary and can't be replaced with an aftermarket unit nor do the aforementioned units come in higher wattage, so that would be a dead end.

You should be looking at a 500W+ unit that is reliable and from a known brand.

4745454b · Mar 22, 2017

So you link an SFX PSU that costs more than normal ATX PSUs that can do the job? Odd.... I'm glad we can all agree that the 240W PSU the op has won't cut it.

It's been a long time since I've heard of Dell using non standard PSUs. The OP should look into size and pin out before buying anything to replace it.

Lutfij · Mar 23, 2017

In retrospect, the unit inside any SFF OptiPlex isn't SFX nor TFX, it's on a form factor of it's own and they only come out of Dell's facility(or shops that are certified to repair Dell OptiPlex device's). I have seen the same PSU on other SFF systems by brands like HP and Lenovo but as you've reminded me, their pinouts are different as well when compared to each other.

Odd how OP hasn't even once mentioned what the make and model of his PSU is nor has he given us a pic to ascertain the unit's value.

4745454b · Mar 23, 2017

I'm guessing if it's that proprietary it can't really be replaced. And 240W is already probably about as high as it goes. (Though there might be a ~300W model.) I'd guess it has 12 or 14A on the 12V rail. (144 or 168W) My guess is the OP needs to stick to a 25-50W card max.

Saga Lout · Mar 24, 2017

When I first read that thread I had to wonder if he was mixing up his Watts and his Volts. Some UK PSUs might describe the Voltage as 240.

4745454b · Mar 24, 2017

That's possible, though many lower end OEM systems have PSUs that small. I think the smallest I ever personally touched was a 144W or 160W. Something like that. I couldn't believe something so small was put into a system.

4745454b · Mar 24, 2017

Using my mod powers I found his other thread. It's a Dell Optiplex 5040. He hasn't replied to that one either so I'm not sure he'll be back.

Vic 40 · Mar 24, 2017

n0ns3ns3 :

Has to do with rail design too,if one strong +12V rail should there be no problem making one six pin go into an 8pin via adapter for instance,but the more +12V rails,also how the power is divided amongst those, the less sure i would be.

n0ns3ns3 · Mar 24, 2017

^ that's true.
I was just trying to explain that 6 and 8 pin connectors are rated much higher than those "imaginary" limits of GPU.

Lutfij · Mar 24, 2017

4745454b,
Thank you for the heads-up bro!

Now to drill more sense into this thread:
Manual for Mini Tower(MT)
Manual for Small Form Factor(SFF)
both within the Dell OptiPlex 5040 range, both are shown to have a proprietary connection to the motherboard and limited connections to it's remaining internal hardware.

Even if the case could accept the GPU, the PSU itself is the limiting factor and since we've covered it, there are no replacement units of higher wattage or aftermarket(higher wattage) units that will literally drop in that chassis.

Simple answer as said before, no you're out of luck on this endeavor. FYI, the OptiPlex's are built/designed for workspace environments and they've made sure that an end user doesn't tamper with the system's innards to maximize reliability.

One more time.

note MT's power connectors

note SFF's power connectors

RealBeast · Mar 24, 2017

MERGED QUESTION
Question from Zane24 : "Customizing Dell Optiplex 5040 (6th gen i5)"

Zane24 :

4745454b :

Yup, proprietary trumps all else here without some serious mod work that the OP likely doesn't have in his skill set (I think that he may have been scared off by this thread, lol).

Gotta go with Lutfij on this one, the hoped upgrade is a total nonstarter.

Is a Radeon 7870 going to run with a 240W PSU?

Prominent

Illustrious

Illustrious

Honorable

Titan

Illustrious

Titan

Illustrious

Illustrious

Illustrious

Titan

Retired Mod

Illustrious

Retired Mod

Titan

Titan

Titan

Titan

Retired Mod

Titan

Titan

Titan

Illustrious

Titan

Titan

Share this page