OCZ 900W modstream can't cope with 3x GPU?

tacotime

legendary

Activity: 1484

Merit: 1005

Quote from: psilan on August 22, 2012, 05:02:54 AM

Crazy, now running 5870,5850,5852,5830 off the single rail 850W...

Great tips guys, thanks.

Yup. The only OCZ psus to get for mining are the Z-series PSUs, which are up there with seasonic/corsair in terms of reliability (I own a 1KW and an 850W).

AndrewBUD

hero member

Activity: 1078

Merit: 502

I have a Antec 620watt High Current Gamer Modular power supply running 4 x 5850's without issue.... The PSU is hardly getting warm.....

Has been running fine for about 4 days now..... I was planning on putting two of them together but I tried 1 and it seems fine

ARapalo

member

Activity: 93

Merit: 10

I think modstream is not OCZ's high end series PSU. And also, if the motherboard doesn't have a dedicated 6-pin (or molex) power for the PCI-e, then you're drawing about 25w of power per GPU through the PCI-e lanes. This might cause some instabilities too.

The-Real-Link

hero member

Activity: 533

Merit: 500

Good to hear it's fixed for you. That original load balancing sounded pretty good so surprised it didn't cut it...

Then again I also avoid OCZ like the plague. Sorry man.

btcnut

member

Activity: 65

Merit: 10

Put the high draw cards on the PCIe power rails, use the low draw cards on the molex rails and you might get away with it

alternatively, try undervolting one or more cards.

jermwerty

sr. member

Activity: 472

Merit: 250

Yeah that PSU has a bunch of 20A rails. Most likely its something like Rail #1: Motherboard, Rail #2 SATA/Molex, Rail #3 PCI-E, Rail #4 PCI-E

So the problem is because you only have three rails you can use to power the GPUs (assuming molex to PCI-E conversions) you can really only use three videocards!

Thats why I love my 5 cards on my single rail (76A) PC Power & Cooling 910W Silencer, draws 750W from the wall and is BAMT stable for months at a time! I also used the same model PS with dual 5970s and it never broke a sweat pulling 620W from the wall.

I have a Rosewill 1KW that has the same issue as the OCZ, too many rails and I only throw two 6950s on it. Sad Sad

AndrewBUD

hero member

Activity: 1078

Merit: 502

PSU's with single rails can handle the load when nothing else is being used....

depends on the PSU

oldDirty

full member

Activity: 182

Merit: 100

roundhouseminer

few wekks ago i run 4 5850 on a Enermax Pro 87+ 600W, 1 AMD Quad, 4Gig, 2 HDD and 5 Fans without any trouble.

psilan

sr. member

Activity: 364

Merit: 250

Crazy, now running 5870,5850,5852,5830 off the single rail 850W...

Great tips guys, thanks.

psilan

sr. member

Activity: 364

Merit: 250

Thanks for the advice. I have a single rail 850W corsair. I will chuck it on the system now

.

ajstar

newbie

Activity: 22

Merit: 0

Single-rail PSU is the only way to go. Mine NZXT Hale90 850W http://www.newegg.com/Product/Product.aspx?Item=N82E16817116012 (on same mobo) handles 5970 + 2x5870 without problems.

Ilikeham

full member

Activity: 238

Merit: 100

Each rail is low amperage, I think the PSU is actually out of spec to the card in fact.

psilan

sr. member

Activity: 364

Merit: 250

Thanks

Sorry I should have mentioned this is a MSI 890fxa-gd70
http://www.msi.com/product/mb/890FXA-GD70.html

Tried and true around here. I blame the PSU. Will find another and put this on my desktop

.

squall1066

copper member

Activity: 2310

Merit: 1032

I'd love to ba able to sugest something but i'm learning myself ATM.

It does sound like the board is not supplying enough watt's across the PCI-E, If you have 1x4 pin on the board, then this might not be enough, I have a rig with three cards and it uses 2x4 pin on the motherboard, another with two cards has 1x4 pin. (irrelivent of single/duel gpu card IMO)

I could be way off, I'm sure someone will point that out.

psilan

sr. member

Activity: 364

Merit: 250

Changed to 5870 5850 5830 and copes. Can't handle the 5970. Must be that great OCZ quality.

psilan

sr. member

Activity: 364

Merit: 250

Just pulled out the 5850. Going nowhere Sad

.

psilan

sr. member

Activity: 364

Merit: 250

How would you balance this?

PSU
Hardwired;
- 8xPCIe
- 8xPCIe
- 6xPCIe

Modular (off HDD labeled area of PSU, no other way)
- 6xPCIe
- 6xPCIe
- 6xPCIe

I initially put 1 of each (hardwired & modular) to each GPU.
Tried 2x hardwired to 5970, rest random.

Not going to well for me here....

psilan

sr. member

Activity: 364

Merit: 250

Mmm ok cool, thanks guys. I will give that a try and update.

crazyates

legendary

Activity: 952

Merit: 1000

Quote from: Coinoisseur on August 18, 2012, 09:10:38 PM

Best guess is you are overdrawing on one or more of those multiple 12V rails.

^^^

Those 3 GPUs shouldn't be using more than 500W, so you should prolly try switching around your load balancing.

Coinoisseur

sr. member

Activity: 336

Merit: 250

Best guess is you are overdrawing on one or more of those multiple 12V rails.

Topic: OCZ 900W modstream can't cope with 3x GPU? (Read 2056 times)