New cruncher(s)? Need some math help ....

[none1]

GOAL is to crunch as much BOINC as possible, and this seems to lead to the conclusion to get the most / cheapest PCIE slots possible.
A company near me is selling some of their older computers, winxp, 160gig drive, 3 gig ram, BUT, they are Ausus A8N-SLI with athalon 64x2 processors.

Key is, the A8N-SLI has TWO Pcie slots .....

They're asking for $250, but I think I can get a couple at $200. The powersupplys are 550 watt, unkown details.

I'm trying to figure out if it would be cheaper $$$ per rac to drop some cuda cards in these, or build a new system.
PRELIM CONCLUSION - given the numbers below, even though I'd rather get sexy new hardware, it looks like the older used systems are cheaper per PCIE slot.
QUESTIONS
1) I'm mostly discounting the processor differences, since it seems CUDA dwarfs the processors in performance. Should I be counting the CPU differences?
2) Should I look at the intel systems? Quick glance looked like multiple PCIE was cheaper on the amd boards.
3) What else should I look at? Should I bump down the specs in the new systems to get a better comparision?


SCENARIOS BELOW
Assume the same PCIE cards to be used in all systems.

OPTION A $700
get THREE of the a8nSLI systems = 6 PCIE slots, three amd64 dual cores

OPTION B = 4pcie slots, $780, and it doesn't look like this would produce much more rac than option A

NEW SYSTEM GUESSes
MB 4 pcie $170
amdx4 3ghz $140
case $60
RAM $230ish
power supply $180

OPTION C GO BIG OR GO HOME $1000, 6 pcie
Gigabyte 6 slot PCIE $250
Amdx6 $200
CASE $120 (big chasis)
ram $230
power supply $200

OPTION D
Sell 6 Geforce 260 cards ( /shrug, $125 each?) buy 6 new geforce 460 cards ($200 each?) total cost $450. ANYONE GOT A GUESS as to how much more rac I'd get with 460s over 260s?

 

[Voodoo Rufus]

http://www.gpureview.com/show_cards.php?card1=577&card2=632

Can't help you much on the GPU side yet. My GTX460 is still stabilizing Rac-wise, but it's putting out at least 8k.

I'd say go big, personally. It might make more sense from a power consumption standpoint as well. Power one big rig with modern components instead of 3 older more inefficient machines. Remember, if you go with 6 PCIE slots, the only way you'll cram six GTX460s into one machine is to water cool all of them, or build two machines.

I would still count the CPUs in for RAC, depending on what they are. Old dual cores won't put out much, but almost any 45nm based quad core is still a potent chip.

 

[QuietIce]

Here's a thread that might interest you. Notice the difference in RAC for cards that are being fed by an inactive core compared to those that aren't? Far better use of processing power to reserve a core to feed a GPU than crunch with it - it least on the newer cards.

http://www.overclockers.com/forums/showthread.php?t=617684

With that in mind I'd love to tell you to buy those old s939 systems but truth is a cheap X3 or X4 Athlon II system with a kickin' motherboard is the best bet. The ASUS M4A79T is a good 4x PCIe board ($170). An X3 ($78) or X4 ($89) CPU is plenty. The same goes for the RAM. No need to spend more than $80 for 2x2 Gb - and that's only because 2x1 Gb isn't that much cheaper ($70) so why not get the extra 2 Gb?

Board: http://www.newegg.com/Product/Product.aspx?Item=N82E16813131363
CPU: http://www.newegg.com/Product/Product.aspx?Item=N82E16819103872 or http://www.newegg.com/Product/Product.aspx?Item=N82E16819103706
Any cheap RAM you want.
Add in the case and you're sitting at $390-400 for a new 4xPCIe rig.

I didn't include the PSU because those 550W used units aren't going to support the cards anyway and I doubt the extra 200-300W for the system is going to make too much of a difference in whatever PSU you'll get to power the cards. If needed you can buy a cheap $50 PSU for the system only and power the cards off a different PSU (it might be cheaper - you'd have to look).

I can also tell you from a logistics stand-point you'll be better off with a single rig. I've been running several s939 systems and am slowly replacing them at 2:1 with single quads (in my case, Phenoms) that use the same power and produce the same heat as a single dual-core system. The heat, power, and space requirements seem trivial but, trust me, they're not unless you're going to park your rigs in the garage or something - and you'll still be burning an extra 140kW hours a month for the second rig.

In short, Option B (modified) is the best bet.



In case you're wondering, yes, I've already been through the numbers - a year or so ago. I looked at Options A and B. Option C wasn't available then and you should check to make sure those cards can run full-out with PCIe X4 slots (X16 layout, X4 data path for slots 5 & 6). Not to mention, as VR pointed out, the problems with squeezing 6 cards onto one board. If you can make all that work then my modifications (lesser CPU and RAM) can also be applied to the six PCIe board. You just don't need a Phenom and a ton of fast RAM to feed the video cards and that's all the CPU should be doing if you have enough cards to keep it busy ...

 

[Jmtyra]

<sneaks into thread>

Don't forget we have other teams, like ::cough:: folding ::cough::

<sneaks out>

 

[Sephis]

<sneaks into thread>

Don't forget we have other teams, like ::cough:: folding ::cough::

<sneaks out>

I thought I already shooed you out of this forum?

Don't make me break out the big guns.

Nah, you folding guys are welcome here. We help each other out a lot in races and such. That makes you guys OK in my book.

 

[none1]

<sneaks into thread>

Don't forget we have other teams, like ::cough:: folding ::cough::

<sneaks out>

Ya, I know, looks like LANDSHARK, whom I used to crunch with, ended up over there while I was away. You can point out to him I passed him in seti if you see him ..............

 

[Duner]

OPTION B = 4pcie slots, $780, and it doesn't look like this would produce much more rac than option A

NEW SYSTEM GUESSes
MB 4 pcie $170
amdx4 3ghz $140
case $60
RAM $230ish
power supply $180

That would be my choice, with the following changes:
MB ~$100, try to get a used AM2+ board, it'll be cheaper than a AM3 board. I like my K9A2 platinum more than my M3AMVP-Dlx because the 4 PCI-E slots are more spread out and can run 4 dual slot cards. The K9A2 supports Phenom X6's if you really want to go there.
CPU ~$100, No need to get a fast quad, just get the lowest one. An X4 620 propus works great.
RAM ~$60, like previously suggested, no need to spend too much on ram here, it won't help
Case $0, come on now, you've officially got a farm. Run Caseless
PSU This is up to you. Running 4 cards can happen with 1 big PSU, but it's probably cheaper to run 2 smaller ones. e.g. Two corsair HX650's is cheaper than the HX1200.