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RX Vega 56/64 on PCI-E 2.0 slot?

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quakerj

New Member
Joined
Oct 28, 2017
I'm planning on purchasing a new GPU for my main PC, which is what I fold and game on. My goal for games is decent (>30 fps) performance at 1440P using high quality settings.

This PC only has PCI Express 2.0. It's a HP Z600 with dual Xeon E5620 CPUs, 12GB DDR3 RAM. Power supply is up for the job (>750w), but it only has one 8-pin connector.

Would a Vega 56/64 run okay in this configuration, or would the PCI-E 2.0 be a bottleneck? I'd like to stick with AMD. I've heard the Vega cards are rather power hungry, do they require 2 8-pin connectors, and if so, would a splitter suffice?

The system functions fine for what I need it for, but the existing Nvidia Quadro 2000 2gb in it is getting a bit long in the tooth for gaming-- I have to dial back settings in a big way to get modern games to run in any playable fashion. Thanks in advance for any help/suggestions.
 

deathman20

High Speed Premium Senior
Joined
Aug 5, 2002
I might be out of date on this but PCI-E 2.0 to PCI-E 3.0 there was very little advantage to switching to the new socket from a performance stand point. Think it was a 2% difference in speed at most, but this was a while back when I looked into this.

Now as for the power connection, there is 2 power connectors on the card. I believe they are both 8-pin but it might vary for each vendor. Though only having 1-8pin connector is a downside you can get cables that make 2x 4pin molex connectors into a 6 or 8pin. Though I wouldn't recommend it for long term and would consider getting a PSU that is suitable for handling the GPU. Do you have a make/model on the PSU?
 
OP
Q

quakerj

New Member
Joined
Oct 28, 2017
After more research, the PSU in question is 650W. The PSU is a proprietary form factor-- this was a $6k system when new. The system currently draws 350W from the power outlet at full CPU and GPU (Quadro 2000) load, taxing the system as much as I can. That number is reported by my UPS, which includes the router, ONT, and other small devices, so it's likely less than that. Only specs I could find were this: https://support.hp.com/us-en/document/c01719966.

The motherboard puts out 75W on the PCI-E card directly, the power supply supposedly is certified for another 75w through the single 8-pin connector.

I find it interesting that the HP power supply specs mention 400hz 118V AC as an acceptable input. That's a military only AC input spec, so I think its likely this is a robust PSU that will handle a new card very easily. I may have to get a second 8-pin connector off a couple unused molex and/or SATA connectors.
 

deathman20

High Speed Premium Senior
Joined
Aug 5, 2002
The GPU isn't a major power sucker in your system using 62W or around that full load.
The CPU's are your major power sucker with that being said not OCed are probably around the 60-80W range per CPU full load. That being said your system is probably drawing 230-250W actual from the PSU since its around 80% or better efficiency. This does give the headroom for the GPU but... they don't have any specific information on the 12V line for the PSU being used. If it can only put out 400W on the 12V line off the PSU... yeah its not going to work. Your going to need at least 500W at least on the PSU's 12V line to run the CPU's and the GPU and even then it might be pushing it.

You can try using Molex connectors for another 8-pin to power the card but do NOT use the SATA connectors at all if you do try that. I've only used 6-pin connector of Molex cables before and they do get toasty with a high wattage GPU... 8-pin could potentially really heat up the cables if its pulling a lot of wattage. Also while the PCI-E says it can supply X amount of amps, realistically the card pulls almost all the power over the power connectors. Less strain on the motherboard power circuits doing that as well.

You might consider linking this topic over in the power supply sub-forum. You would probably get a lot of answers quickly from some of our experts to get a little more clarity on this.