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Hi guys,

My current PC: Core 2 Q6600 @ 3.0Ghz, HIS HD4850 512MB fully stock GPU, HP ZR24W monitor + 37" Samsung LCD TV, 450W Thermaltake TR2 QFan PSU with only one 6-pin connector ( http://www.anandtech.com/show/2670 ), Gigabyte MB with P41T chipset.

There are some deals for AMD cards at the moment, and I was thinking of getting a HD7850 2GB. The model I would like to get is a Sapphire Radeon HD7850 Dual-X 2GB (11200-07-20G) because it has the output connections I want (DVI-D, DVI-VGA, HDMI, full size Display Port), and it fits inside my case. But after reading user reviews and searching the net for problems I might face, it seems that many people are complaining about some issues, most worrying beeing flicker when running on a DVI-VGA analogue connection (flicker may not be the best way to describe it, but my english is not that good and I can't think of a better word right now...) and black screens / computer freeze after some time running games. I really need the VGA connection to work properly for my Samsung TV (on my TV, VGA simply works better than HDMI - lower input lag, better image quality, better settings available when in VGA/PC mode, and the panel doesn't turn off when showing a full black image like it does when connected through HDMI, which is VERY annoying considering it's a CCFL LCD panel and I can't turn this "feature" off). My current HD4850 doesn't have any issues when I use a DVI to VGA adapter.

Also, from what I was able to find out, the HD7850 needs 2 x 6-pin power connections, my PSU only has one available and I would have to use an extra molex to 6pin adapter.

My questions:
- Do you guys think my PSU can handle a HD7850 and a Q6600 @ 3.0GHz?
- Is anyone with a HD7850 using a DVI-VGA analogue connection and has no issues with it? Could the problem some users are experiencing be due to poor cables or some misconfiguration?

if you look at tr's 7850 review, you'll see it top out at 182 watts (for the xfx version) under load (they used a core i5-750, 4 gig ram). a power supply is typically most efficient at 50% load, so your 450 watter should be fine. i can't help you with your other concerns.

Thank you for your answer, yes that's what I thought as well, but wanted to ask just to be sure, since my PSU wasn't made for cards with more than one 6-pin connector, and my CPU already draws about 140W.

It depends on your PSU, really. The two 12V rails on your Thermaltake are rated at 16A and 17A.

I used to run a Q9550 (95W like the Q6600) and the good-quality Antec 380W PSU just didn't have enough current to run a 150W GTX460 when I upgraded to that, and the 12V rails were rated at 17A and 15A - very similar indeed.


The 7850 is only 130W but my GTX460 was only a 768MB version with a disabled memory controller which means it probably didn't suck down 150W.
Your overclocked Q6600 is probably sucking down an extra 40-50W, as you say 140W total. I think it will be cutting it fine, especially with that overclock too.

AMD:
◾PCI Express® based PC is required with one X16 lane graphics slot available on the motherboard
◾500W (or greater) power supply with one 75W 6-pin PCI Express power connector recommended
◾600W power supply (or greater) with two 75W 6-pin PCI Express power connectors recommended for AMD CrossFire™ technology.
◾Certified power supplies are recommended. Refer to http://ati.amd.com/certifiedPSU for a list of Certified products
◾Minimum 4GB of system memory
◾8GB (or more) of system memory recommended for AMD CrossFire™ technology
◾Installation software requires CD-ROM drive, a keyboard, a mouse, and a display
◾DVD playback requires DVD drive and a DVD
◾Blu-ray™ playback requires Blu-ray drive and a Blu-ray disc
◾For an AMD CrossFire™ system, a second AMD Radeon™ HD 7850 GPU, an AMD CrossFire™ Ready motherboard and one AMD CrossFire™ Bridge Interconnect cable is required
◾Use of 3 or more displays with AMD Eyefinity technology requires a DisplayPort-capable panel or an AMD Eyefinity validated dongle. See http://www.amd.com/EyefinityDongles for a list of validated DisplayPort dongles.
◾64-bit operating system highly recommended
◾Not for industrial or commercial use. See AMD FirePro™ Graphics solutions for these applications.

Those are the system requirements, be wary of the power supply you are using, as capacitor aging may come back to haunt you. I would possibly upgrade the Power Supply while you are upgrading the CPU.

Techgoudy wrote:

Those are the system requirements

GPU manufacturers' recommendations are not very useful because: a system running an 220W TDP AMD FX-9590 with 5 hdds, a hefty number of expansion cards, 8 case fans, 2 dvd burners......and a 7850 is going to require MUCH more power than a 55W i3-3220 barebones system using the same card. Use a PSU Calculator or take measured power consumption numbers from reviews and roughly double it for a recommended PSU wattage. (pay attention to the system specs used to get those numbers of course)

How long have you had that PSU, and how much longer do you plan on keeping it? I would have to agree that getting a new PSU probably isn't a bad idea (500W would be enoughif you want to OC) if you bought it in 2008 when it came out. Keep in mind that each successive hardware generation uses less power to accomplish more performance. A new PSU like this Corsair CX 500 for $40 after MIR doesn't have to break the bank and will perform just fine, but if you can afford something better like an 80Plus Gold rated unit, I would recommend it. (peace-of-mind and better longevity)

The Sapphire 7850 only requires one 6-pin PCIe power connector. If you're concerned about power draw, you could buy a power meter and/or lower your processor OC.

I currently have a similar setup with a an overclocked Athlon II x4 630. I have been running the HD7850 at 1050core1300memory up from 900core1200memory with zero issues. I have a corsair cx400w power supply that is powering all of it including a HDD, SDD, 4 fans and a DVD drive. I can't imagine you would have a problem with your thermal take PSU providing enough power.

DPete27 wrote:

Techgoudy wrote:

Those are the system requirements

How long have you had that PSU? I would have to agree that getting a new PSU with the proper 6-pin connectors probably isn't a bad idea (500W would be enough). Keep in mind that each successive hardware generation uses less power to accomplish more performance. A new PSU like this Corsair CX 500 for $40 after MIR doesn't have to break the bank and will perform just fine, but if you can afford something better like an 80Plus Gold rated unit, I would recommend it. (peace-of-mind and better longevity)

Not very long, slightly less than 3 years (long story why the PSU is newer than the rest of the system). I will upgrade the PSU when I'll upgrade the whole system, but unfortunately Haswell hasn't excited me that much so I think I'll postpone the upgrade for now. Yes, Haswell is a lot faster and more power efficient than my Q6600, but the high temps and limited overclock potential are a turn-off. I don't want to upgrade the PSU at this point, I'd rather underclock the GPU if necessary.

Anyway, I was actually more worried about the other issues I mentioned (VGA issues, black screens, system freeze etc). I want a decent GPU that is rock-stable first, speed comes second. I was wondering if those issues affect only some samples, or the whole HD78xx series.

kroker wrote:

Also, from what I was able to find out, the HD7850 needs 2 x 6-pin power connections

My 7850 card only uses a single 6-pin power connector. And it runs fine on my 450W power supply. Check my sig for system specs.

Yeah, I was just going to write as well - the 7850 uses just 1 PCI 6-pin connector. Its TDP is ~130W or something like that.

My 7850 2GB is running 2 Xeon 5160's at 3.0GHz so the performance is similar to what you would get - CPU bottlenecks depend on the game. I can get 60FPS in StarCraft 2 during most games, ~25FPS when there's a mothership involved.

kroker wrote:

Anyway, I was actually more worried about the other issues I mentioned (VGA issues, black screens, system freeze etc). I want a decent GPU that is rock-stable first, speed comes second. I was wondering if those issues affect only some samples, or the whole HD78xx series.

We have a "fleet" of about 40 workstations with either 7800 or 7900 cards in them because they're decent at cranking through OpenCL renderers for Rhino and 3DSMax.
Most of them are connected via displayport or DVI but the nodes in the renderfarm are all connected to a KVM using VGA connectors (with adapters) and none of them have issues that I'm aware of.

Chrispy_ wrote:

We have a "fleet" of about 40 workstations with either 7800 or 7900 cards in them because they're decent at cranking through OpenCL renderers for Rhino and 3DSMax.
Most of them are connected via displayport or DVI but the nodes in the renderfarm are all connected to a KVM using VGA connectors (with adapters) and none of them have issues that I'm aware of.

Thank you, that's good to know.