Buying 6870 or 6850, performance and price question

[Davste]

The Powercolor 6870 is a reference design. It's just under 10 inches long.

As for the power supply, it looks like your unit is circa-2004. It likely doesn't have sufficient power on the 12v rail to support the 6870. I'm sure it doesn't have two PCIe power cables, which you'd need for the 6870, although the card may come with an adapter. The 6850 may work, but again, it would be cutting it close (you should give us the specs off the label of your PSU).

Honestly, I might consider just picking up a holdover card like an HD5670, which draws very little power, and would probably provide double the performance of your 7800GTX. There's one available at your store for 80 euros: http://www.simarksupplies.com/ShowProduct.aspx/Product/P13756-XFX-Radeon-HD5670-1024MB. Not a great deal, but your old system is sufficiently out-of-date that these new graphics cards really may not work.

I think I might be sorry that I got a 5670 when I get a new CPU/mobo in the future. However if my PSU won't take it, or it doesn't fit, I will consider it. It still looks like a decent card.

The 6870 is much, much bigger (in physical size) than an nvidia 7800 right? My Nvidia 7800 fits in nicely and I also have a spare inch and a half. Does anyone know how thick it is?

 

[Davste]

that would barely qualify as a typical 350 watt psu so I can not believe they call that a 500 watt psu. 22 amps on the 12v is not really sufficient for a full system with a decent video card. plus that psu is likely made with inferior components to begin with. you are going to need a better power supply to reliably run your system.

my 420W has 18 amps on the 12v. Do you need the rest of the label? I think the 420W is a good power supply anyway, doesn't look cheap.

are you sure the 6870 won't work on 500W with 22a?
here it says the 6870 needs around 12.5a on the 12v rail, but I need to leave more power for the rest of the system. With my current CPU/MOBO I don't think it will take that much power/When I upgrade though, I would definitely need to get a new one.

http://www.overclock.net/amd-ati/913872-amps-needed-12v-rail-6800s.html

What do you think? Next monday I'm going to buy a graphics card anyway. Hopefully not the 5670

 

[toyota]

a 420 watt psu with only 18 amps is likely going to be a cheaply made product. that 500 watt psu with 22 amps probably cannot even make that in real world conditions since it likely uses very cheap parts. even if it did provide 22 amps that is not enough to safely power a full system with a 6870.

 

[Davste]

a 420 watt psu with only 18 amps is likely going to be a cheaply made product. that 500 watt psu with 22 amps probably cannot even make that in real world conditions since it likely uses very cheap parts. even if it did provide 22 amps that is not enough to safely power a full system with a 6870.

okay.
the new one does have two pciE power cables though, I checked right now. Could I at least be able to run the 6850 on it?

 

[toyota]

okay.
the new one does have two pciE power cables though, I checked right now. Could I at least be able to run the 6850 on it?

2 pci-e 6 pin connectors on that psu? that seems a bit odd. are you sure that psu only makes 22 amps on the 12v?

 

[Davste]

2 pci-e 6 pin connectors on that psu? that seems a bit odd. are you sure that psu only makes 22 amps on the 12v?

nope, I made a mistake. It was something else. Only one pci-e.
Are you sure the 420W/500W one can't run the 6850?

If no, these are the 3 best stores in malta:
http://scanmalta.com/
http://klikk.com.mt/#home
http://www.simarksupplies.com/

What's the best price for a PSU that can do the job. Thank you very much for your help and time.

 

[edplayer]

get this one:

http://klikk.com.mt/index.php?supercatid=2&catid=22&productid=6938&productname=Corsair%20Builder%20Series%20430%20Watt%20PSU


Pretty good quality and good price compared to the other choices


Edit: it only has one PCI-E connector but it is of good enough quality to handle a 6870 long term (you will need to use an adapter for the other pci-e connector, should come with the videocard)

 

[Davste]

One more question about my current PSU.
Remember that I won't be using the full potential of my graphics card, due to my CPU. Won't this fact greatly reduce the load on the graphics card, maybe even allowing me to use my current PSU for a 6850?

I don't know, I just want to make sure I've gone through the possibilities. It's probably either a 50 euro PSU + 6850 or a 5670.

get this one:

http://klikk.com.mt/index.php?supercatid=2&catid=22&productid=6938&productname=Corsair%20Builder%20Series%20430%20Watt%20PSU


Pretty good quality and good price compared to the other choices


Edit: it only has one PCI-E connector but it is of good enough quality to handle a 6870 long term (you will need to use an adapter for the other pci-e connector, should come with the videocard)

It's got a 28A 12V rail. Are you sure it's enough?

 

[edplayer]

If you plan on sticking with a 6870 class or lower card, yes. Xbit labs tested it (the 6870) to use 125W while gaming. We use 120V here, don't know if that matters.


Here is a review on it from a trusted site that specializes in power supply reviews:

http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=214


I think it might be the best psu in that price range from the choices you linked. Don't recognize many of those brands on the sites you listed but Corsair is a very well regarded psu brand in the U.S. and that model is an entry model but it still is good quality.

Lots of those psus for sale don't even list the specs on the site!

Are you sure the 420W/500W one can't run the 6850?

They might be able to. Xbit labs tested it (the 6850) to use 91W. Say about 8A. If the only possible outcomes were it to work or not work, I would say just try it. But there is a small chance that other things might get damaged. I would say it is a small chance but you should know that it is possible.

 

[Davste]

If you plan on sticking with a 6870 class or lower card, yes. Xbit labs tested it (the 6870) to use 125W while gaming. We use 120V here, don't know if that matters.


Here is a review on it from a trusted site that specializes in power supply reviews:

http://www.jonnyguru.com/modules.php?name=NDReviews&op=Story&reid=214


I think it might be the best psu in that price range from the choices you linked. Don't recognize many of those brands on the sites you listed but Corsair is a very well regarded psu brand in the U.S. and that model is an entry model but it still is good quality.

Lots of those psus for sale don't even list the specs on the site!





They might be able to. Xbit labs tested it (the 6850) to use 91W. Say about 8A. If the only possible outcomes were it to work or not work, I would say just try it. But there is a small chance that other things might get damaged. I would say it is a small chance but you should know that it is possible.

Okay. I won't risk damaging my card by underpowering it, and I hope this PSU works well I made a bit for it, hopefully I could get it at 36 euros, looks like nobody is bidding and it's going to close in a day. Our voltage is 240v here bdw.

 

[Davste]

It looks like the 430w is not good enough. Look here:

Any other options? According to this, I was underpowering my Nvidia 7800GTX. I'm not so sure.
I used http://www.thermaltake.outervision.com/Power and it shows that my system consumes around 235W, without the graphics card.
The HD6850 consumes around 127W, so that leaves us pretty safe at 362W. What do you think?

 

[edplayer]

mmm, it doesn't say the model number and there have been multiple XFX Radeon 6850 so I can't really check.

I'm sure someone here that is more familiar with Radeon cards will have a good estimate.

 

[Termie]

mmm, it doesn't say the model number and there have been multiple XFX Radeon 6850 so I can't really check.

I'm sure someone here that is more familiar with Radeon cards will have a good estimate.

I run a GTX460 on a Corsair 400w power supply with 30a on the 12v rail. Granted, my e8400 uses a bit less power than the X2 the OP is using, but it isn't that significant a difference. I only pull 200w at load, and the GTX460 uses more power than the 6870, and much more power than the 6850. You migth say "what, only 200w, but I have a 500w PSU?!?" - well, that's not the issue. The issue is the 12v rail, which is where almost all the power is drawn, and the quality of the components used, which is what determines longevity and ability to withstand fluctuations.

OP - that Corsair CX430 is definitely sufficient. Don't worry about what those PSU calculators say...they assume your PSU is junk! The Corsair is not junk, and it can very capably power a 6850 or a 6870. I'm going to switch my suggestion again, however, and now go to the XFX 6850, for the following reasons:

(1) It uses less power (maybe about 30w less)
(2) It only needs one power connector. Yes, the cards usually come with adapters, but in your situation, better safe than sorry.
(3) XFX is a good brand
(4) It's the cheapest card you mentioned and now you're going to need to spend some money on a PSU
(5) It will draw the least power while still being much, much stronger than a 7800gtx. The difference between 4x faster and 4.1 faster would probably be lost on you anyway!
(6) The 6850 is barely any longer than a 7800gtx, while the 6870 is significantly longer

But one caveat: I hope your case/motherboard can fit a double-slot cooler - have you checked that Davste? Nothing in the slot below, and two vent openings at the back of the case?

This will be the beginning of a very nice 2500k build, once you get around to it. In case you're wondering about supporting a quad-core and a video card of this caliber, my 5850 (which is exactly equivalent to the 6870 in power draw) along with my i7-860 draws about 235w at stock and under 300w overclocked. You will have plenty of power to support a 2500k - it's much more efficient than my i7-860.

 

[Davste]

I run a GTX460 on a Corsair 400w power supply with 30a on the 12v rail. Granted, my e8400 uses a bit less power than the X2 the OP is using, but it isn't that significant a difference. I only pull 200w at load, and the GTX460 uses more power than the 6870, and much more power than the 6850. You migth say "what, only 200w, but I have a 500w PSU?!?" - well, that's not the issue. The issue is the 12v rail, which is where almost all the power is drawn, and the quality of the components used, which is what determines longevity and ability to withstand fluctuations.

OP - that Corsair CX430 is definitely sufficient. Don't worry about what those PSU calculators say...they assume your PSU is junk! The Corsair is not junk, and it can very capably power a 6850 or a 6870. I'm going to switch my suggestion again, however, and now go to the XFX 6850, for the following reasons:

(1) It uses less power (maybe about 30w less)
(2) It only needs one power connector. Yes, the cards usually come with adapters, but in your situation, better safe than sorry.
(3) XFX is a good brand
(4) It's the cheapest card you mentioned and now you're going to need to spend some money on a PSU
(5) It will draw the least power while still being much, much stronger than a 7800gtx. The difference between 4x faster and 4.1 faster would probably be lost on you anyway!
(6) The 6850 is barely any longer than a 7800gtx, while the 6870 is significantly longer

But one caveat: I hope your case/motherboard can fit a double-slot cooler - have you checked that Davste? Nothing in the slot below, and two vent openings at the back of the case?

This will be the beginning of a very nice 2500k build, once you get around to it. In case you're wondering about supporting a quad-core and a video card of this caliber, my 5850 (which is exactly equivalent to the 6870 in power draw) along with my i7-860 draws about 235w at stock and under 300w overclocked. You will have plenty of power to support a 2500k - it's much more efficient than my i7-860.

Spot on. Thank you soooo much, great answer I might actually get that PSU for 36 euros if there aren't any bidders.

Double slot cooler... not sure what that means exactly. Does it mean it uses the space of two PCI slots instead of one? I can send a picture of the back of my case if need be. I do have a free PCI slot right above my graphics card though, there's a small piece of metal between the two slots, I'm not sure if it will interfere.

I also measured my case. It should be able to take a 6850 with half an inch to spare.

 

[Termie]

Spot on. Thank you soooo much, great answer I might actually get that PSU for 36 euros if there aren't any bidders.

Double slot cooler... not sure what that means exactly. Does it mean it uses the space of two PCI slots instead of one? I can send a picture of the back of my case if need be. I do have a free PCI slot right above my graphics card though, there's a small piece of metal between the two slots, I'm not sure if it will interfere.

I also measured my case. It should be able to take a 6850 with half an inch to spare.

Unless your motherboard is inverted, you'll need a free slot below the PCIe slot. The metal separator at the end of the two slots is not a problem.

 

[Davste]

I'm going to get my 6850 tomorrow

When I get it, do you suggest I overclock it immediately?
I heard that overclocking new cards can increase the overclocking headroom?
I'm not sure, and excuse me if I got anything wrong. I stand to be corrected.
Do you think it is a good idea?

 

[betasub]

^ Test it at stock first to make sure it works perfectly at warrantied specs.

 

[Chinoman]

I recently bought an Asus Direct CU 6850 1GB for my system and boy it's been great!

I have the core overclocked at 900 Mhz have seen great strides in performance as opposed to running stock. From comparing my overclocked benchmark scores to those of the 6870 at stock, I saw only a miniscule difference.

6850 is cheap, fast and has a generous overclocking headroom. You won't regret the purchase.

 

[Davste]

The 6870 went on sale, I can afford it now. I need a reply quickly:

My PSU (the corsair one I just bought) has only one PCIe power cable. It has 28A on the 12v rail.
I have a (2) 4 pin molex to (1) 6 pin PCIe adapter, however I have only ONE available molex slot,
the others have been used by hard drives, cd drives etc...
Can I just use one molex and leave it at that?

 

[Chinoman]

No, if the card doesn't get adequate power, you will notice artifacting and general performance issues.

 

[Termie]

The 6870 went on sale, I can afford it now. I need a reply quickly:

My PSU (the corsair one I just bought) has only one PCIe power cable.
I have a x2 4 pin molex to 6 pin PCIe adapter, however I have only ONE available molex slot,
the others have been used by hard drives, cd drives etc...
Can I just use one molex and leave it at that?

I seriously doubt that using only one molex would work (although I can't say I've ever experimented with that on my system). I'd say the 6850 is still your best option. It's plenty fast.

 

[Davste]

No, if the card doesn't get adequate power, you will notice artifacting and general performance issues.

So can I use a Y splitter to take power from the connector sharing with the CD drive instead, to get another molex? I never use my CD while gaming anyway.

 

[Davste]

I seriously doubt that using only one molex would work (although I can't say I've ever experimented with that on my system). I'd say the 6850 is still your best option. It's plenty fast.

Yes it's quite fast, and it can get close to the 6870 in speed if you overclock it, but I don't like to overclock graphics cards. There's around a 15% performance difference between them, but due to this power problem I might still have to get a 6850.

 

[Chinoman]

So can I use a Y splitter to take power from the connector sharing with the CD drive instead, to get another molex? I never use my CD while gaming anyway.

You could do that.

 

[Davste]

Haven't completely decided yet

Would you say it's a good idea to use the splitter though? What if I actually would want to use my DVD-RW drive while gaming? Could the extra load cause crashes, or unreliable performance? Don't know if anyone has done it before here, and I would like some opinions, altough in general I don't think it's a really good idea, it sounds messy...