I want to get a new GPU, and I was thinking about something along these lines...Gigabyte Radeon HD 7770 1GB GDDR5 DX11 DVI HDMI 2xMiniDP PCI-E

This card requires PCIe 3.0

My motherboard is, pretty old. http://www.asus.com/Motherboards/Intel_Socket_775/P5K/#specifications

On that page it says my mobo has PCIe x16. But I can't really make the distinction between what I need and what I have. Does PCIe x16 answer the 3.0 version which the GPU needs? In other, simple and plain words - Will this GPU be compatible with my mobo?

Regarding power supply, I have a 500w PSU, and the card GPU needs 450w, so I am covered there. Any help will be appreciated on the matter.


This card requires PCIe 3.0 No it does not.

This card is compatible with PCIe version 3, but will work in a PCIe v2 slot.

Regarding power supply, I have a 500w PSU, and the card GPU needs 450w, so I am covered there.

Sadly not true. The cards needs power in specific voltages and amperages. You will need to check how much power it requires on the +12v rails and how much power your PSU can deliver on those rail(s). (E.g. a PSU delivering up to 1oo watt on the +5 volt, 200 watt on 3.3 volt and 150 watt on +12 volt will not do if your GPU needs more than 150 Watt of +12v. - Note that these numbers are fictional, but a PSU does deliver +3.3v, +5v and +12 volt lines and it never can deliver all of its power on a single line).

You also want to check if the card uses extra power connectors (it probably does since the PCIe spec only allows a card to draw 75 watt from the motherboard and most high end cards use up to 188 Watt - Again a PCIe cap. More is not allowed). These extra connectors come in different flavours (8pins and 6 pins) and some cards require more than one.

Update: I just looked at a picture of the gigabyte 7770 and it has one 6 pin connector.

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  • This is my PSU coolermaster.com/product.php?product_id=3738 - What do you make of it? – user6004 Oct 28 '12 at 22:07
  • The specs on that page includes: AD input/DC output +12 v 18A. That is 216 Watt (12*18) per +12v rail. (they list two rails, but you will only connect one). Since no PCIe card may need more than 188 Watt this rail will do for all PCIe cards. – As for connectors, it lists both PCI-e 6+2 pin connector x2 and under cable it lists PCI-e 6 Pin x 1. Seems inconsistent, but you only need one PCI-e 6 pin, so that part will also do. – Efficientcy is listed as 70+%, which is quite low. – Hennes Oct 28 '12 at 22:22

PCIe is backwards compatible. So in this situation, the 7770 will be fine. As for your PSU, it may not be enough depending on the brand. If its a garbage PSU by Raidmax, Coolmax, etc, you may have trouble powering the card. A quality brand like Antec, XFX, Seasonic, etc will be good though.

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