GTX 970 with antec vp-450

[Vaughan129]

Will my antec vp-450(12 volt rail 18 amp dual rail) support a gtx 970. It has less power consumption than my r9 270x, which I've overclocked and it's running fine, but I see people saying that I need a 600w, why? The r9 270x has a minimum requirement of 500w so that isn't argument. (I'm running an fx 6300 too)

 

[turkey3_scratch]

Labelled wattage means diddly squat on PSUs, so that's why it supports it. So do "minimum requirements". Labelled wattage ignores the fact that there are PSUs that blow when creating current that merits half the rated wattage, and there are units that manage to surpass the rated wattage even, particularly for brief moments, while having safe voltage values within ATX specification.

When it comes to PSUs, what is important is how much current on each rail can be created (think of a rail as a group of wires sharing the same voltage) until the internal components in the PSU either melt or burn, the PSU shuts itself off due to its protections, or voltages are out of specification, all happening at its rated temperature.

Basically, in even simpler terms, the wattage sticker on a PSU means nothing. Only what is tested by professional reviewers matters, so that is why when people talk of things like "you need a 600W unit for this or that" they are incorrect because they are basing units off labelled wattage solely. Minimum requirements are also false, because they ignore rails and the fact that there are junk units out there.

 

[Vaughan129]

Labelled wattage means diddly squat on PSUs, so that's why it supports it. So do "minimum requirements". Labelled wattage ignores the fact that there are PSUs that blow when creating current that merits half the rated wattage, and there are units that manage to surpass the rated wattage even, particularly for brief moments, while having safe voltage values within ATX specification.

When it comes to PSUs, what is important is how much current on each rail can be created (think of a rail as a group of wires sharing the same voltage) until the internal components in the PSU either melt or burn, the PSU shuts itself off due to its protections, or voltages are out of specification, all happening at its rated temperature.

Basically, in even simpler terms, the wattage sticker on a PSU means nothing. Only what is tested by professional reviewers matters, so that is why when people talk of things like "you need a 600W unit for this or that" they are incorrect because they are basing units off labelled wattage solely. Minimum requirements are also false, because they ignore rails and the fact that there are junk units out there.

What about in my case, is my psu okay.

 

[turkey3_scratch]

Here is a review of your unit: http://www.hardwaresecrets.com/antec-vp450-power-supply-review/

I would maybe not actually run the GTX 970 on it, and here is why. First thing you need to understand is a rail. This unit has two 12V rails. A rail is just a group of wires linked to an overcurrent protection. Overcurrent protection is managed by a chip in the power supply, and what it does it detects if too much current is being drawn from that group of wires (whether it be a ton by one wire or an equal distribution across a bunch), and it'll then shut down the power supply. Each rail in this unit is rated for 18 amps or 216W.

One rail in this unit solely powers the CPU. The other rail powers everything else, including the GPU, the HDD, fans, motherboard, etc. That is insufficient for this GPU, and I suspect that if you overclock the GTX 970 more or if you run an actual stress test, your unit will shut down. a GTX 970 under stress can draw 250W+. Temperature plays a role, too; as temperature inside the unit increases, the ability for each rail to create more current decreases. In addition, if you have Rails A, B, C, and D, when there is load on B, C, and D, the potential for rail A decreases, so that is even less current that can be created for those wires.

According to this review, the unit seems to shut off after drawing 264W from one of the 12V rails, so you may actually be alright now that I think about it. Usually the overcurrent protection kicks in later than what that rail is actually rated for. Seeing as this unit has its protections all working, actually, I'd say you are safe to use it.

 

[Vaughan129]

Here is a review of your unit: http://www.hardwaresecrets.com/antec-vp450-power-supply-review/

I would maybe not actually run the GTX 970 on it, and here is why. First thing you need to understand is a rail. This unit has two 12V rails. A rail is just a group of wires linked to an overcurrent protection. Overcurrent protection is managed by a chip in the power supply, and what it does it detects if too much current is being drawn from that group of wires (whether it be a ton by one wire or an equal distribution across a bunch), and it'll then shut down the power supply. Each rail in this unit is rated for 18 amps or 216W.

One rail in this unit solely powers the CPU. The other rail powers everything else, including the GPU, the HDD, fans, motherboard, etc. That is insufficient for this GPU, and I suspect that if you overclock the GTX 970 more or if you run an actual stress test, your unit will shut down. a GTX 970 under stress can draw 250W+. Temperature plays a role, too; as temperature inside the unit increases, the ability for each rail to create more current decreases. In addition, if you have Rails A, B, C, and D, when there is load on B, C, and D, the potential for rail A decreases, so that is even less current that can be created for those wires.

According to this review, the unit seems to shut off after drawing 264W from one of the 12V rails, so you may actually be alright now that I think about it. Usually the overcurrent protection kicks in later than what that rail is actually rated for. Seeing as this unit has its protections all working, actually, I'd say you are safe to use it.

Thank you!

 

[photonboy]

Hey,
What will happen is that you'll get roughly:

1) 75W via motherboard
2) 75W via 6-pin PCIe
3) remainder via MOLEX adapter

My guess is that the 24-pin and 6-pin PCIe cable are using the same 12V Rail.

The CPU and MOLEX connections are probably using the other rail.

Basically, it would PROBABLY be okay, though I'm not comfortable saying that for sure, especially without knowing what else is attached and if any overclocking of the CPU is going on. Considering the cost of a GTX970 I'd probably get a quality 650W PSU.

(I also don't know how much of the CPU power is supplied via the 24-pin motherboard cable, if any, because if it didn't supply any then the 8/4-pin connector to the CPU would have to supply it all. Thus, if the MOLEX had to supply up to 100W and the CPU took 90W then one of the 12V rails may need to supply 190W continuously. That's about 100% load on the rail, so see my dilemma?)

Again, I may have some facts incorrect.

Also, not sure what limits power draw via the 6-pin PCIe cable and what happens if it tried to draw say 100W?

*For one thing, the FAN NOISE is likely to be pretty high when you heavily load the Antec VP450 (or most power supplies), so for that reason alone I'd get a different power supply.

 

[turkey3_scratch]

Hardwaresecrets says only the CPU cable is on 12V1, it says all other cables are 12V2. But realistically, 12V1 will go nowhere near the 216W it's rated for with a single CPU, it'll be less than half of that, so 12V2 should be sufficient for a GTX 970 + 50W for rest of stuff. The protection kicks in at 264W for 12V2, so as long as he doesn't overclock that 970 I think he'll be okay, though if it does shut down he'll know why

 

[Vaughan129]

Hey,
What will happen is that you'll get roughly:

1) 75W via motherboard
2) 75W via 6-pin PCIe
3) remainder via MOLEX adapter

My guess is that the 24-pin and 6-pin PCIe cable are using the same 12V Rail.

The CPU and MOLEX connections are probably using the other rail.

Basically, it would PROBABLY be okay, though I'm not comfortable saying that for sure, especially without knowing what else is attached and if any overclocking of the CPU is going on. Considering the cost of a GTX970 I'd probably get a quality 650W PSU.

(I also don't know how much of the CPU power is supplied via the 24-pin motherboard cable, if any, because if it didn't supply any then the 8/4-pin connector to the CPU would have to supply it all. Thus, if the MOLEX had to supply up to 100W and the CPU took 90W then one of the 12V rails may need to supply 190W continuously. That's about 100% load on the rail, so see my dilemma?)

Again, I may have some facts incorrect.

Also, not sure what limits power draw via the 6-pin PCIe cable and what happens if it tried to draw say 100W?

*For one thing, the FAN NOISE is likely to be pretty high when you heavily load the Antec VP450 (or most power supplies), so for that reason alone I'd get a different power supply.

My r9 270x runs just fine,meaning that the cpu is supplied just fine.

 

[turkey3_scratch]

All these power supply topics are arising tonight where the numbers get very close and the mathematics very precise. I need a break from these

It might not be a bad idea to get a new unit Vaughan. Even if it does work, you're loading it to its max potential, so I don't expect the capacitors to hold up a lone time.

 

[photonboy]

Not comfortable recommending this now.

Max Load is 360W on both 12V rails. I don't know if you can fully draw that due to the way the rails split the load. This supplies:

1) Graphics card
2) CPU
3) 12V fans

I've seen the GTX970 overclocked go to around 250W.

Total load here is 129W, though not sure exactly how much is CPU (12Volt):
http://www.hardwarecanucks.com/forum/hardware-canucks-reviews/57615-amd-vishera-fx-6300-fx-4300-review-14.html

I would have to subtract the GTX670 idle power draw, and the other 5V/3.3V stuff but let's just say 110W? Add 10W for fans maybe etc.

250+110+10

370W

Someone correct me if I'm doing something stupid with my calculations but my conclusion is really that it's POSSIBLE ignoring overclock and spikes in usage but really, really NOT recommended.

 

[photonboy]

R9-270X vs GTX970:

You keep saying your overclocked R9-270X will use more power than a GTX970. Where are you getting this information from?

I've seen models from both which have 2x6-pin connectors so it depends on the card. Also, by my calculations you're really close to the power limit with your setup so a bit more could put you over the edge.

 

[turkey3_scratch]

I agree, not recommended, but he is using it now, and it's fine ATM. of course, I don't expect the games he plays to put major stress on it compared to a stress test.

A GTX 970 at reference clocks is in the 175W vicinity. So, 12V2 so far has 175W + fans and rest of system so 225W-? That's the way I'm sort of thinking of his here.

I think by time we get this nit-picky with numbers, he probably should actually get a new unit, but the good news is that the protections are working properly. I'd be much more concerned if the protections kicked in after voltages were unstable, but Hardwaresecrets says the voltages were still well within specification when OCP kicked in at 264W, and the unit posed no fire hazard.

I guess this is why some people dislike multirails. This is a poor design IMO because the CPU is on one rail and everything else is shoved onto the other. Poor distribution IMO.

 

[photonboy]

I agree, not recommended, but he is using it now, and it's fine ATM. of course, I don't expect the games he plays to put major stress on it compared to a stress test.

A GTX 970 at reference clocks is in the 175W vicinity. So, 12V2 so far has 175W + fans and rest of system so 225W-? That's the way I'm sort of thinking of his here.

I think by time we get this nit-picky with numbers, he probably should actually get a new unit, but the good news is that the protections are working properly. I'd be much more concerned if the protections kicked in after voltages were unstable, but Hardwaresecrets says the voltages were still well within specification when OCP kicked in at 264W, and the unit posed no fire hazard.

I guess this is why some people dislike multirails. This is a poor design IMO because the CPU is on one rail and everything else is shoved onto the other. Poor distribution IMO.

Do you have a better way?
The point is to limit power draw through any particular point. It's a safety thing.

Plus, we only usually have design issues when we try using adapters. Basically when we ignore the recommended models for our hardware.

 

[turkey3_scratch]

My better way would be the PCIe cable on its own rail, then stick the CPU/motherboard/molex/SATA power all on the other rail. The current rail distribution would make more sense if this PSU could handle 2 CPUs, but it is only has one CPU EPS12V cable. I guess you could run an FX 9xxx on it, that'd be the benefit, but I think putting the PCIe cable on its own rail is better.

Wait one second. Color me confused. This unit only has a single 6-pin PCIe cable. How in the first place does it even power a GTX 970?

 

[Vaughan129]

What PSU should I get?

 

[turkey3_scratch]

PCPartPicker part list / Price breakdown by merchant

Power Supply: SeaSonic S12II 520W 80+ Bronze Certified ATX Power Supply ($59.17 @ Newegg)
Total With 10% Tax: $59.17
Total Without Tax: $53.98
Prices include shipping, taxes, and discounts when available
Generated by PCPartPicker 2016-03-15 22:26 EDT-0400