# How to Calculate and Power Your Mining GPU’s

When you are calculating PSU size you should use the TDP  (Thermal Design Power ) wattage rating, not the operating wattage you are pulling at the wall plug.

When an electronics device is powered on, or runs hot, it can pull up to the TDP wattage amount, therefore all calculations need to be based on that scenario.

http://www.geeks3d.com/…/graphics-cards-thermal-design-pow…/
(unfortunately does not have all GPUs listed)

The formula is as follows;

System (MOBO + CPU) = 150W (This is an assumption; CPU 35W to 65W, MOBO 65W to 100W)
Number of GPUs x TDP wattage
Add the System and total GPU wattage together
Add a 20% safety factor by multiplying the total by 1.2
This formula will put your operating wattage in the 50% to 60% sweet spot for efficiency as well.

Example;

```System = 150W
6 GPUs with a TDP of 150W = 900W
150W + 900W = 1050W
1050W x 1.2 = 1260W```
1. So you would need at least a 1200W PSU to run that rig, 1300W would be better still.
2. You need the same number of VGA PCIe Power Lines as you have GPUs
3. You need at least half the Number of SATA lines as you have GPUs
4. So find a Bronze or better rated 1200W PSU with at least 6 VGA PCIe Power Lines 8-Pin (6+2) and at least 3 Peripheral SATA Power Lines.

The version is less important than the quality, if you buy cheap risers your going to have a large amount that are defective or fail. I have seen batch of brand new ver 008s from Amazon and they were all bad, and had to be returned, I bought some cheap ver 007 off eBay and they all sucked.

If you read the reviews on many of them people actually just give in and say oh well, at least 2 are always bad, its just how it is. If you buy name brand, five star rated ones, guess what? They all work. Buying good quality risers is important, spend a few extra dollars, much less aggravation and headaches.

The Version refers to the PC board configuration, and a newer version does not necessarily mean it’s better. Here is a list of PCIe Riser versions;

Ver. 003 4-Pin Molex to SATA Power
Ver. 004 4-Pin Molex to SATA Power
Ver. 005 4-Pin Molex to SATA Power
Ver. 006 May be 6-Pin or 4-Pin Molex
Ver. 006C 6-Pin PCI-E power to 15-pin SATA power cable
Ver. 006S 4-Pin Molex to SATA Power
Ver. 007 6-Pin PCI-E power to 15-pin SATA power cable, Voltage Regulator and Fuse
Ver. 007C 6-Pin PCI-E power to 15-pin SATA power cable
Ver. 007S SATA Direct plug in power (No adapter cable)
Ver. 008S Three power inputs SATA direct, 6-Pin, and 4-Pin Molex (No adapter cable)
Ver. 009 6-Pin PCI-E power to 15-pin SATA power cable
Ver. 009S Three power inputs SATA direct, 6-Pin, and 4-Pin Molex 6-Pin to SATA adapter

There is a lot of misinformation about 4-Pin Molex and SATA risers and connectors.

All x16 graphics cards are limited to a PCIe draw of 75 Watts. The 75W maximum can be drawn from the +12V and +3.3V rails, and the total draw on the two rails cannot exceed 75W.

This is a power up maximum, not a continuous operating draw. Most GPUs pull less than one third of their operating power from the x16 PCIe slot, so if your operating wattage is 150W then the card is getting 50W or less from the riser. A large majority of GPUs pull 45 Watts or less. If your GPUs use more than 180 watts, or are drawing more than 50W from the PCIe slot on the riser then you will have to power the risers with a VGA PCIe power line.

Some older Cards like the R9 Series, and the HD series may draw more. Some models of the newer high end cards like the GTX 1070, 1070Ti, 1080, 1080Ti, and most certainly the Vega 56 and 64.

4-Pin Molex connectors do not have a +3.3V pin, they only have +5V, which is not used here, and a +12V pin which can handle 60 Watts maximum. (see attached picture)

I have seen and used a two Molex to 6-Pin connector for GPU power slots, you can only do this on cards rated for a TDP of 120W or less. Check the link to the chart to find out if your GPU uses more or less.

SATA connectors also have a +5V which is not used, and they have +3.3V pins which can handle 14.85 Watts, and three +12V pins which can handle 18W each, or 54W, for a total maximum of 68.85 Watts. For powering risers just count the +12V or 54W.

The recommendation is never to connect more than two (2) risers per Molex or SATA line, the reason for this has more to do with overloading an individual peripheral rail. On single rail PSUs you could connect three to a line without overloading the line.

It is never advisable to connect SATA to any GPU power slot.