Jump to content
EwinRacing Flash Series Gaming Chairs
rossysaurus

GTX970 + Dell DA-2 test results

Recommended Posts

RE: GTX970 W/Dell DA-2 power supply:

I have done some more testing and although not yet conclusive I am seeing a pattern. I have been experimenting with MSi Afterburner to adjust power requirements and I believe we are simply running out of power from the 220 watt Dell DA-2.

Possible causes:

Efficiency:

Lets assume the DA-2 has 75%-80% full load efficiency (which seems to be reported by some picoPC forums). This gives us a power of 165 - 176 watts available. The GTX 970 reference card is rated at 145 watt TDP. Zotac do not state what their cards max TDP is, but we shall assume it is slightly more due to the slight overclock and dual fan cooling, lets say 150 watt. Now GPU-Z reports the power consumption boosts to 110% of TDP when required. This gives us a peak power consumption of 165 watt, exactly what the DA-2 can provide @75% efficiency.

Bullshit power ratings:

Midway through writing this post I found this review detailing the exact power requirements of the GTX 970 and 980 cards:

A New Power Consumption Test Setup - Nvidia GeForce GTX 970 And 980 Review: Maximum Maxwell

There are 3 pages of power consumption results and it is well worth a read through all three as it is very interesting.

In summary NVIDIA lied about the power consumption and although it's average power consumption is lower than similar performing cards it peak and requirements under gaming load are just as high or higher, at times peaking up to 300 watt and consistently sitting around 250 watt under full load.

After reading this I am surprised I can run this thing at all from the Dell DA-2 220 watt power supply!

Voltage/Current:

The toms hardware article clearly shows that at times the card requires more than 12 volts. the DA-2 has been shown to operate closer to 11.7v than 12, and with the GTX 970 peaking over 13v and spending much of its time over 12.5v.

Although the GTX 970 is not shown, the GTX 980 shows amperage spikes over 20A and up to 24A at times. This is significantly more than the DA-2 can provide.

Software Solutions:

I have had some success here and have not had a bluescreen with these settings yet.

Underclocking - I have dropped my core clock speeds down by 100mhz, bringing the core clock down to the same as the NVIDIA reference cards (1177mhz).

Power throttling - When set to 100% the card boosted to 110%. I have adjusted the "power" slider in MSi Afterburner to 80%. This is to prevent the card from exceeding the 145 watt TDP. The card still boosts to 94% peak, even when limited to 80%.

Driver Tweaks - In NVIDIA control panel i have changed the power management mode to "prefer maximum performance". This locks the card at 1177mhz clock speed and prevents sudden fluctuations in power requirements. The default is set to "adaptive" which specifically fluctuates the power to reduce overall power consumption but with unknown effects on peak draw.

There is another option labelled "prefer consistent performance" but I cannot find out exactly what it does or how it differs from Max performance. I would assume it disables boost but I've done that manually with the underclock.

Hardware Solutions:

Standard ATX power supply - and live with the fan noise, mess and size.

A big-ass capacitor - This would smooth out the voltage and current peaks and drops during unexpected power loads.

Link two DA-2 together? - Cut and link the 2 sets of signal cables together but run one DA-2 to the PE4C to provide power to the board and PCI slot, then convert the other DA-2 to a PCI power plug to power the card directly. Both would turn on at the same time from the signal cables but would double the available power.

Corrections on GPU-Z PerfLimit

Basically any reason given is the reason the card has reached peak performance, not necessarily a fault. It is normal for GPU-Z to display something here, as the card is either under utilised (util) or at maximum performance.

Vop + VMax = graphics card has reached maximum voltage permitted through drivers (1.2v) though may not have reached maximum clock speeds.

Pwr = Card is running at max clock speeds but does not require full voltages.

pwr + Vop + VMax = everything is maxed

----------------------------------------------------------------------------------------------------------------------------------------------------------------------------

EDIT: I have just finished a 3 hour gaming session in Far Cry 3 without a single issue :)

i kept the clocks at 1177mhz max but upped my power limit to 90%, which produced power peaks of 98% and GPU loads of 98% (interestingly GPU-Z logs show the card has never exceeded 98% load under any test, benchmark or configuration). Temps remained constant at 75*C and fan speed never exceeded 50%.

Interestingly the Voltages averaged 1.1620, and the card spent very little time at the 1.2v max.

The DA-2 is now quite warm to the touch but has not tripped into protection mode, making me think it is overcurrent or overvoltage protection that is the issue, not thermal.

  • Thumbs Up 3

Share this post


Link to post
Share on other sites

@rossysaurus

Very nice!

My Zotac GTX970 seems to peak around 180W (using watt meter) so maybe that's too much for the DA-2.

Weird enough I can reproduce the black out-problem by running Sky Diver demo in 3Dmark, it happens just after she has landed and just before entering the big cave opening.

This rules out the temp issue since my DA-2 is not hot to the touch.

I'm more into the voltage drop issue, I should try to measure the voltages during the test once and for all to see what's going on.

Share this post


Link to post
Share on other sites

@rossysaurus

VOLTAGE RAMP UP

I'm pretty sure know what the problem is now, not 'over current protection' but rather 'voltage ramp up time', this triggers the DA-2 to shut off.

A theory is that this is implemented on purpose to prevent us for using the DA-2 as an ATX PSU (I don't know about that).

I follow this thread for info:

SPCR • View topic - Dell DA-2 Power Brick Help

BAD MOLEX CONNECTORS

There seem to be huge voltage drop off in the DA-2 cable and molex connectors as well, some users had success using screw type terminals in order to prevent these drops:

"don't use a molex connector, splice+solder the wires directly, or install a screw type terminal. I am currently using the latter. Voltage at the brick is 12.4v, at the Pico it's 12.14. Before that it was dropping to 11.5v with a molex conenctor"

REPRODUCABLE BLACKOUT SCENARIO

The 'voltage ramp up time' theory seems to be be in line with my symptom benching the Sky Diver demo, the demo normally goes black for a 1/4 second and then full load the right after (like a cut scene), this triggers the DA-2 to black out.

Sooo, a pico PSU in between seems to smooth things out for most people, the answer lies in there, but what?... caps?

TESTINGS

In order to rule a bad Molex connection of my last DA-2 setup I'll now do this:

Working scenario as reference:

Akitio PCB + x16 slot: Powered by Akitio PSU (just connecting it as usual)

GPU: ATX 2 x 6-pin

= No problem at all.

Test of possibly bad Molex connection to the slot:

Akitio PCB + x16 slot: Powered by Akitio PSU

GPU: Powered by DA-2 (have to make a 2 x 6pin connector for it)

If this works, then the problem lies in molex connector, but I highly doubt it.

MAXWELL GPU & POWER SPIKES

Here is a very interesting article about the power spikes in the Maxwell arhitecure:

http://www.tomshardware.com/reviews/nvidia-geforce-gtx-980-970-maxwell,3941-11.html

Share this post


Link to post
Share on other sites

I even got 220W with a overclocked GTX 970. No board partner is sticking to the TDP.

Share this post


Link to post
Share on other sites

AHA! that concludes it really!

I was so damn tired of the black outs and voltage drops I was experiencing when gaming @ stock clocks with the EXP GDC+Radeon HD 7950 powered by that Dell DA-2,

Before I was plugging the adapter in a 5 outlet power strip and I experienced a lot of black outs, I decided to plug the thing directly at the wall and since then I did not experience a blackout, that wall outlet placement was very crucial to my wife that I again purchased a wall 3 way power strip and since then I had the black outs again...

Plugging the DA-2 directly to the wall theoretically eliminates (at stock clocks and voltage settings) black outs so you guys might consider this setup too as another experimentation.

Building a PC soon....

Skylake please come! and MSI GS 30 shadow please release it!

  • Thumbs Up 1

Share this post


Link to post
Share on other sites

Well that's interesting, I had an EVGA 780 Ti SC card which was over clocked. The manufacturer stated a maximum power draw of 250W so I thought that the 300W PSU in the Sonnet III-D should be enough to power it. Then when I started Unigine Valley, the computer crashed within 5 seconds.

I'm just hoping that the III-D's PSU is enough for a stock clocked 980 :/

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

×

Important Information

By using this site, you agree to our Terms of Use. We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.